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• DBA Best Practices - A Blog Series: Episode 1 - Backups

  - by Argenis

    This blog post is part of the DBA Best Practices series, on which various topics of concern for daily database operations are discussed. Your feedback and comments are very much welcome, so please drop by the comments section and be sure to leave your thoughts on the subject. Morning Coffee When I was a DBA, the first thing I did when I sat down at my desk at work was checking that all backups had completed successfully. It really was more of a ritual, since I had a dual system in place to check for backup completion: 1) the scheduled agent jobs to back up the databases were set to alert the NOC in failure, and 2) I had a script run from a central server every so often to check for any backup failures. Why the redundancy, you might ask. Well, for one I was once bitten by the fact that database mail doesn't work 100% of the time. Potential causes for failure include issues on the SMTP box that relays your server email, firewall problems, DNS issues, etc. And so to be sure that my backups completed fine, I needed to rely on a mechanism other than having the servers do the taking - I needed to interrogate the servers and ask each one if an issue had occurred. This is why I had a script run every so often. Some of you might have monitoring tools in place like Microsoft System Center Operations Manager (SCOM) or similar 3rd party products that would track all these things for you. But at that moment, we had no resort but to write our own Powershell scripts to do it. Now it goes without saying that if you don't have backups in place, you might as well find another career. Your most sacred job as a DBA is to protect the data from a disaster, and only properly safeguarded backups can offer you peace of mind here. "But, we have a cluster...we don't need backups" Sadly I've heard this line more than I would have liked to. You need to understand that a cluster is comprised of shared storage, and that is precisely your single point of failure. A cluster will protect you from an issue at the Operating System level, and also under an outage of any SQL-related service or dependent devices. But it will most definitely NOT protect you against corruption, nor will it protect you against somebody deleting data from a table - accidentally or otherwise. Backup, fine. How often do I take a backup? The answer to this is something you will hear frequently when working with databases: it depends. What does it depend on? For one, you need to understand how much data your business is willing to lose. This is what's called Recovery Point Objective, or RPO. If you don't know how much data your business is willing to lose, you need to have an honest and realistic conversation about data loss expectations with your customers, internal or external. From my experience, their first answer to the question "how much data loss can you withstand?" will be "zero". In that case, you will need to explain how zero data loss is very difficult and very costly to achieve, even in today's computing environments. Do you want to go ahead and take full backups of all your databases every hour, or even every day? Probably not, because of the impact that taking a full backup can have on a system. That's what differential and transaction log backups are for. Have I answered the question of how often to take a backup? No, and I did that on purpose. You need to think about how much time you have to recover from any event that requires you to restore your databases. This is what's called Recovery Time Objective. Again, if you go ask your customer how long of an outage they can withstand, at first you will get a completely unrealistic number - and that will be your starting point for discussing a solution that is cost effective. The point that I'm trying to get across is that you need to have a plan. This plan needs to be practiced, and tested. Like a football playbook, you need to rehearse the moves you'll perform when the time comes. How often is up to you, and the objective is that you feel better about yourself and the steps you need to follow when emergency strikes. A backup is nothing more than an untested restore Backups are files. Files are prone to corruption. Put those two together and realize how you feel about those backups sitting on that network drive. When was the last time you restored any of those? Restoring your backups on another box - that, by the way, doesn't have to match the specs of your production server - will give you two things: 1) peace of mind, because now you know that your backups are good and 2) a place to offload your consistency checks with DBCC CHECKDB or any of the other DBCC commands like CHECKTABLE or CHECKCATALOG. This is a great strategy for VLDBs that cannot withstand the additional load created by the consistency checks. If you choose to offload your consistency checks to another server though, be sure to run DBCC CHECKDB WITH PHYSICALONLY on the production server, and if you're using SQL Server 2008 R2 SP1 CU4 and above, be sure to enable traceflags 2562 and/or 2549, which will speed up the PHYSICALONLY checks further - you can read more about this enhancement here. Back to the "How Often" question for a second. If you have the disk, and the network latency, and the system resources to do so, why not backup the transaction log often? As in, every 5 minutes, or even less than that? There's not much downside to doing it, as you will have to clear the log with a backup sooner than later, lest you risk running out space on your tlog, or even your drive. The one drawback to this approach is that you will have more files to deal with at restore time, and processing each file will add a bit of extra time to the entire process. But it might be worth that time knowing that you minimized the amount of data lost. Again, test your plan to make sure that it matches your particular needs. Where to back up to? Network share? Locally? SAN volume? This is another topic where everybody has a favorite choice. So, I'll stick to mentioning what I like to do and what I consider to be the best practice in this regard. I like to backup to a SAN volume, i.e., a drive that actually lives in the SAN, and can be easily attached to another server in a pinch, saving you valuable time - you wouldn't need to restore files on the network (slow) or pull out drives out a dead server (been there, done that, it’s also slow!). The key is to have a copy of those backup files made quickly, and, if at all possible, to a remote target on a different datacenter - or even the cloud. There are plenty of solutions out there that can help you put such a solution together. That right there is the first step towards a practical Disaster Recovery plan. But there's much more to DR, and that's material for a different blog post in this series.

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• Restoring databases to a set drive and directory

  - by okeofs

   Restoring databases to a set drive and directory Introduction Often people say that necessity is the mother of invention. In this case I was faced with the dilemma of having to restore several databases, with multiple ‘ndf’ files, and having to restore them with different physical file names, drives and directories on servers other than the servers from which they originated. As most of us would do, I went to Google to see if I could find some code to achieve this task and found some interesting snippets on Pinal Dave’s website. Naturally, I had to take it further than the code snippet, HOWEVER it was a great place to start. Creating a temp table to hold database file details First off, I created a temp table which would hold the details of the individual data files within the database. Although there are a plethora of fields (within the temp table below), I utilize LogicalName only within this example. The temporary table structure may be seen below:   create table #tmp ( LogicalName nvarchar(128)  ,PhysicalName nvarchar(260)  ,Type char(1)  ,FileGroupName nvarchar(128)  ,Size numeric(20,0)  ,MaxSize numeric(20,0), Fileid tinyint, CreateLSN numeric(25,0), DropLSN numeric(25, 0), UniqueID uniqueidentifier, ReadOnlyLSN numeric(25,0), ReadWriteLSN numeric(25,0), BackupSizeInBytes bigint, SourceBlocSize int, FileGroupId int, LogGroupGUID uniqueidentifier, DifferentialBaseLSN numeric(25,0), DifferentialBaseGUID uniqueidentifier, IsReadOnly bit, IsPresent bit,  TDEThumbPrint varchar(50) )    We now declare and populate a variable(@path), setting the variable to the path to our SOURCE database backup. declare @path varchar(50) set @path = 'P:\DATA\MYDATABASE.bak'   From this point, we insert the file details of our database into the temp table. Note that we do so by utilizing a restore statement HOWEVER doing so in ‘filelistonly’ mode.   insert #tmp EXEC ('restore filelistonly from disk = ''' + @path + '''')   At this point, I depart from what I gleaned from Pinal Dave.   I now instantiate a few more local variables. The use of each variable will be evident within the cursor (which follows):   Declare @RestoreString as Varchar(max) Declare @NRestoreString as NVarchar(max) Declare @LogicalName  as varchar(75) Declare @counter as int Declare @rows as int set @counter = 1 select @rows = COUNT(*) from #tmp  -- Count the number of records in the temp                                    -- table   Declaring and populating the cursor At this point I do realize that many people are cringing about the use of a cursor. Being an Oracle professional as well, I have learnt that there is a time and place for cursors. I would remind the reader that the data that will be read into the cursor is from a local temp table and as such, any locking of the records (within the temp table) is not really an issue.   DECLARE MY_CURSOR Cursor  FOR  Select LogicalName  From #tmp   Parsing the logical names from within the cursor. A small caveat that works in our favour,  is that the first logical name (of our database) is the logical name of the primary data file (.mdf). Other files, except for the very last logical name, belong to secondary data files. The last logical name is that of our database log file.   I now open my cursor and populate the variable @RestoreString Open My_Cursor  set @RestoreString =  'RESTORE DATABASE [MYDATABASE] FROM DISK = N''P:\DATA\ MYDATABASE.bak''' + ' with  '   We now fetch the first record from the temp table.   Fetch NEXT FROM MY_Cursor INTO @LogicalName   While there are STILL records left within the cursor, we dynamically build our restore string. Note that we are using concatenation to create ‘one big restore executable string’.   Note also that the target physical file name is hardwired, as is the target directory.   While (@@FETCH_STATUS <> -1) BEGIN IF (@@FETCH_STATUS <> -2) -- As long as there are no rows missing select @RestoreString = case  when @counter = 1 then -- This is the mdf file    @RestoreString + 'move  N''' + @LogicalName + '''' + ' TO N’’X:\DATA1\'+ @LogicalName + '.mdf' + '''' + ', '   -- OK, if it passes through here we are dealing with an .ndf file -- Note that Counter must be greater than 1 and less than the number of rows.   when @counter > 1 and @counter < @rows then -- These are the ndf file(s)    @RestoreString + 'move  N''' + @LogicalName + '''' + ' TO N’’X:\DATA1\'+ @LogicalName + '.ndf' + '''' + ', '   -- OK, if it passes through here we are dealing with the log file When @LogicalName like '%log%' then    @RestoreString + 'move  N''' + @LogicalName + '''' + ' TO N’’X:\DATA1\'+ @LogicalName + '.ldf' +'''' end --Increment the counter   set @counter = @counter + 1 FETCH NEXT FROM MY_CURSOR INTO @LogicalName END   At this point we have populated the varchar(max) variable @RestoreString with a concatenation of all the necessary file names. What we now need to do is to run the sp_executesql stored procedure, to effect the restore.   First, we must place our ‘concatenated string’ into an nvarchar based variable. Obviously this will only work as long as the length of @RestoreString is less than varchar(max) / 2.   set @NRestoreString = @RestoreString EXEC sp_executesql @NRestoreString   Upon completion of this step, the database should be restored to the server. I now close and deallocate the cursor, and to be clean, I would also drop my temp table.   CLOSE MY_CURSOR DEALLOCATE MY_CURSOR GO   Conclusion Restoration of databases on different servers with different physical names and on different drives are a fact of life. Through the use of a few variables and a simple cursor, we may achieve an efficient and effective way to achieve this task.

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• DBA Best Practices - A Blog Series: Episode 1 - Backups

  - by Argenis

    This blog post is part of the DBA Best Practices series, on which various topics of concern for daily database operations are discussed. Your feedback and comments are very much welcome, so please drop by the comments section and be sure to leave your thoughts on the subject. Morning Coffee When I was a DBA, the first thing I did when I sat down at my desk at work was checking that all backups have completed successfully. It really was more of a ritual, since I had a dual system in place to check for backup completion: 1) the scheduled agent jobs to back up the databases were set to alert the NOC in failure, and 2) I had a script run from a central server every so often to check for any backup failures. Why the redundancy, you might ask. Well, for one I was once bitten by the fact that database mail doesn't work 100% of the time. Potential causes for failure include issues on the SMTP box that relays your server email, firewall problems, DNS issues, etc. And so to be sure that my backups completed fine, I needed to rely on a mechanism other than having the servers do the taking - I needed to interrogate the servers and ask each one if an issue had occurred. This is why I had a script run every so often. Some of you might have monitoring tools in place like Microsoft System Center Operations Manager (SCOM) or similar 3rd party products that would track all these things for you. But at that moment, we had no resort but to write our own Powershell scripts to do it. Now it goes without saying that if you don't have backups in place, you might as well find another career. Your most sacred job as a DBA is to protect the data from a disaster, and only properly safeguarded backups can offer you peace of mind here. "But, we have a cluster...we don't need backups" Sadly I've heard this line more than I would have liked to. You need to understand that a cluster is comprised of shared storage, and that is precisely your single point of failure. A cluster will protect you from an issue at the Operating System level, and also under an outage of any SQL-related service or dependent devices. But it will most definitely NOT protect you against corruption, nor will it protect you against somebody deleting data from a table - accidentally or otherwise. Backup, fine. How often do I take a backup? The answer to this is something you will hear frequently when working with databases: it depends. What does it depend on? For one, you need to understand how much data your business is willing to lose. This is what's called Recovery Point Objective, or RPO. If you don't know how much data your business is willing to lose, you need to have an honest and realistic conversation about data loss expectations with your customers, internal or external. From my experience, their first answer to the question "how much data loss can you withstand?" will be "zero". In that case, you will need to explain how zero data loss is very difficult and very costly to achieve, even in today's computing environments. Do you want to go ahead and take full backups of all your databases every hour, or even every day? Probably not, because of the impact that taking a full backup can have on a system. That's what differential and transaction log backups are for. Have I answered the question of how often to take a backup? No, and I did that on purpose. You need to think about how much time you have to recover from any event that requires you to restore your databases. This is what's called Recovery Time Objective. Again, if you go ask your customer how long of an outage they can withstand, at first you will get a completely unrealistic number - and that will be your starting point for discussing a solution that is cost effective. The point that I'm trying to get across is that you need to have a plan. This plan needs to be practiced, and tested. Like a football playbook, you need to rehearse the moves you'll perform when the time comes. How often is up to you, and the objective is that you feel better about yourself and the steps you need to follow when emergency strikes. A backup is nothing more than an untested restore Backups are files. Files are prone to corruption. Put those two together and realize how you feel about those backups sitting on that network drive. When was the last time you restored any of those? Restoring your backups on another box - that, by the way, doesn't have to match the specs of your production server - will give you two things: 1) peace of mind, because now you know that your backups are good and 2) a place to offload your consistency checks with DBCC CHECKDB or any of the other DBCC commands like CHECKTABLE or CHECKCATALOG. This is a great strategy for VLDBs that cannot withstand the additional load created by the consistency checks. If you choose to offload your consistency checks to another server though, be sure to run DBCC CHECKDB WITH PHYSICALONLY on the production server, and if you're using SQL Server 2008 R2 SP1 CU4 and above, be sure to enable traceflags 2562 and/or 2549, which will speed up the PHYSICALONLY checks further - you can read more about this enhancement here. Back to the "How Often" question for a second. If you have the disk, and the network latency, and the system resources to do so, why not backup the transaction log often? As in, every 5 minutes, or even less than that? There's not much downside to doing it, as you will have to clear the log with a backup sooner than later, lest you risk running out space on your tlog, or even your drive. The one drawback to this approach is that you will have more files to deal with at restore time, and processing each file will add a bit of extra time to the entire process. But it might be worth that time knowing that you minimized the amount of data lost. Again, test your plan to make sure that it matches your particular needs. Where to back up to? Network share? Locally? SAN volume? This is another topic where everybody has a favorite choice. So, I'll stick to mentioning what I like to do and what I consider to be the best practice in this regard. I like to backup to a SAN volume, i.e., a drive that actually lives in the SAN, and can be easily attached to another server in a pinch, saving you valuable time - you wouldn't need to restore files on the network (slow) or pull out drives out a dead server (been there, done that, it’s also slow!). The key is to have a copy of those backup files made quickly, and, if at all possible, to a remote target on a different datacenter - or even the cloud. There are plenty of solutions out there that can help you put such a solution together. That right there is the first step towards a practical Disaster Recovery plan. But there's much more to DR, and that's material for a different blog post in this series.

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• How can I keep a graphics object centered (like a circle) when zooming in or out on it?

  - by sonny5

  using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; using System.Drawing.Drawing2D; using System.Drawing.Imaging; namespace testgrfx { public class Form1 : System.Windows.Forms.Form { float m_Scalef; float m_Scalefout; Rectangle m_r1; private System.Windows.Forms.Button button2; private System.Windows.Forms.Button button3; private System.ComponentModel.Container components = null; private void InitializeComponent() { m_Scalef = 1.0f; // for zooming purposes Console.WriteLine("opening m_Scalef= {0}",m_Scalef); m_Scalefout = 1.0f; Console.WriteLine("opening m_Scalefout= {0}",m_Scalefout); m_r1 = new Rectangle(50,50,100,100); this.AutoScrollMinSize = new Size(600,700); this.components = new System.ComponentModel.Container(); this.button2 = new System.Windows.Forms.Button(); this.button2.BackColor = System.Drawing.Color.LightGray; this.button2.Location = new System.Drawing.Point(120, 30); this.button2.Name = "button2"; this.button2.Size = new System.Drawing.Size(72, 24); this.button2.TabIndex = 1; this.button2.Text = "Zoom In"; this.button2.Click += new System.EventHandler(this.mnuZoomin_Click); this.Controls.Add(button2); this.button3 = new System.Windows.Forms.Button(); this.button3.BackColor = System.Drawing.Color.LightGray; this.button3.Location = new System.Drawing.Point(200, 30); this.button3.Name = "button3"; this.button3.Size = new System.Drawing.Size(72, 24); this.button3.TabIndex = 2; this.button3.Text = "Zoom Out"; this.button3.Click += new System.EventHandler(this.mnuZoomout_Click); this.Controls.Add(button3); //InitMyForm(); } public Form1() { InitializeComponent(); Text = " DrawLine"; BackColor = SystemColors.Window; // Gotta load these kind at start-up ... not with button assignments this.Paint+=new PaintEventHandler(this.Form1_Paint); } static void Main() { Application.Run(new Form1()); } /// Clean up any resources being used. protected override void Dispose( bool disposing ) { if( disposing ) { if (components != null) { components.Dispose(); } } base.Dispose( disposing ); } // autoscroll2.cs does work private void Form1_Paint(object sender, System.Windows.Forms.PaintEventArgs e) { Graphics dc = e.Graphics; dc.PageUnit = GraphicsUnit.Pixel; dc.PageScale = m_Scalef; Console.WriteLine("opening dc.PageScale= {0}",dc.PageScale); dc.TranslateTransform(this.AutoScrollPosition.X/m_Scalef, this.AutoScrollPosition.Y/m_Scalef); Pen pn = new Pen(Color.Blue,2); dc.DrawEllipse(pn,m_r1); Console.WriteLine("form_paint_dc.PageUnit= {0}",dc.PageUnit); Console.WriteLine("form_paint_dc.PageScale= {0}",dc.PageScale); //Console.Out.NewLine = "\r\n\r\n"; // makes all double spaces } private void mnuZoomin_Click(object sender, System.EventArgs e) { m_Scalef = m_Scalef * 2.0f; Console.WriteLine("in mnuZoomin_Click m_Scalef= {0}",m_Scalef); Invalidate(); // to trigger Paint of entire client area } // try: System.Drawing.Rectangle resolution = Screen.GetWorkingArea(someForm); private void Form1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e) { // Uses the mouse wheel to scroll Graphics dc = CreateGraphics(); dc.TranslateTransform(this.AutoScrollPosition.X/m_Scalef, this.AutoScrollPosition.Y/m_Scalef); Console.WriteLine("opening Form1_MouseDown dc.PageScale= {0}", dc.PageScale); Console.WriteLine("Y wheel= {0}", this.AutoScrollPosition.Y/m_Scalef); dc.PageUnit = GraphicsUnit.Pixel; dc.PageScale = m_Scalef; Console.WriteLine("frm1_moudwn_dc.PageScale= {0}",dc.PageScale); Point [] mousep = new Point[1]; Console.WriteLine("mousep= {0}", mousep); // make sure to adjust mouse pos.for scroll position Size scrollOffset = new Size(this.AutoScrollPosition); mousep[0] = new Point(e.X-scrollOffset.Width, e.Y-scrollOffset.Height); dc.TransformPoints(CoordinateSpace.Page, CoordinateSpace.Device,mousep); Pen pen = new Pen(Color.Green,1); dc.DrawRectangle(pen,m_r1); Console.WriteLine("m_r1= {0}", m_r1); Console.WriteLine("mousep[0].X= {0}", mousep[0].X); Console.WriteLine("mousep[0].Y= {0}", mousep[0].Y); if (m_r1.Contains(new Rectangle(mousep[0].X, mousep[0].Y,1,1))) MessageBox.Show("click inside rectangle"); } private void Form1_Load(object sender, System.EventArgs e) { } private void mnuZoomout_Click(object sender, System.EventArgs e) { Console.WriteLine("first line--mnuZoomout_Click m_Scalef={0}",m_Scalef); if(m_Scalef > 9 ) { m_Scalef = m_Scalef / 2.0f; Console.WriteLine("in >9 mnuZoomout_Click m_Scalef= {0}",m_Scalef); Console.WriteLine("in >9 mnuZoomout_Click__m_Scalefout= {0}",m_Scalefout); } else { Console.WriteLine("<= 9_Zoom-out B-4 redefining={0}",m_Scalef); m_Scalef = m_Scalef * 0.5f; // make it same as previous Zoom In Console.WriteLine("<= 9_Zoom-out after m_Scalef= {0}",m_Scalef); } Invalidate(); } } // public class Form1 }

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• Why do I get a nullpointerexception at line ds.getPort in class L1?

  - by Fred

  import java.awt.; import java.awt.event.; import javax.swing.; import java.io.; import java.net.; import java.util.; public class Draw extends JFrame { /* * Socket stuff */ static String host; static int port; static int localport; DatagramSocket ds; Socket socket; Draw d; Paper p = new Paper(ds); public Draw(int localport, String host, int port) { d = this; this.localport = localport; this.host = host; this.port = port; try { ds = new DatagramSocket(localport); InetAddress ia = InetAddress.getByName(host); System.out.println("Attempting to connect DatagramSocket. Local port " + localport + " , foreign host " + host + ", foreign port " + port + "..."); ds.connect(ia, port); System.out.println("Success, ds.localport: " + ds.getLocalPort() + ", ds.port: " + ds.getPort() + ", address: " + ds.getInetAddress()); Reciever r = new Reciever(ds); r.start(); } catch (Exception e) { e.printStackTrace(); } setDefaultCloseOperation(EXIT_ON_CLOSE); getContentPane().add(p, BorderLayout.CENTER); setSize(640, 480); setVisible(true); } public static void main(String[] args) { int x = 0; for (String s : args){ if (x==0){ localport = Integer.parseInt(s); x++; } else if (x==1){ host = s; x++; } else if (x==2){ port = Integer.parseInt(s); } } Draw d = new Draw(localport, host, port); } } class Paper extends JPanel { DatagramSocket ds; private HashSet hs = new HashSet(); public Paper(DatagramSocket ds) { this.ds=ds; setBackground(Color.white); addMouseListener(new L1(ds)); addMouseMotionListener(new L2()); } public void paintComponent(Graphics g) { super.paintComponent(g); g.setColor(Color.black); Iterator i = hs.iterator(); while(i.hasNext()) { Point p = (Point)i.next(); g.fillOval(p.x, p.y, 2, 2); } } private void addPoint(Point p) { hs.add(p); repaint(); } class L1 extends MouseAdapter { DatagramSocket ds; public L1(DatagramSocket ds){ this.ds=ds; } public void mousePressed(MouseEvent me) { addPoint(me.getPoint()); Point p = me.getPoint(); String message = Integer.toString(p.x) + " " + Integer.toString(p.y); System.out.println(message); try{ byte[] data = message.getBytes("UTF-8"); //InetAddress ia = InetAddress.getByName(ds.host); String convertedMessage = new String(data, "UTF-8"); System.out.println("The converted string is " + convertedMessage); DatagramPacket dp = new DatagramPacket(data, data.length); System.out.println(ds.getPort()); //System.out.println(message); //System.out.println(ds.toString()); //ds.send(dp); /*System.out.println("2Sending a packet containing data: " +data +" to " + ia + ":" + d.port + "...");*/ } catch (Exception e){ e.printStackTrace(); } } } class L2 extends MouseMotionAdapter { public void mouseDragged(MouseEvent me) { addPoint(me.getPoint()); Point p = me.getPoint(); String message = Integer.toString(p.x) + " " + Integer.toString(p.y); //System.out.println(message); } } } class Reciever extends Thread{ DatagramSocket ds; byte[] buffer; Reciever(DatagramSocket ds){ this.ds = ds; buffer = new byte[65507]; } public void run(){ try { DatagramPacket packet = new DatagramPacket(buffer, buffer.length); while(true){ try { ds.receive(packet); String s = new String(packet.getData()); System.out.println(s); } catch (Exception e) { e.printStackTrace(); } } } catch (Exception e) { e.printStackTrace(); } } }

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• PASS Summit 2010 BI Workshop Feedbacks

  - by Davide Mauri

  As many other speakers already did, I’d like to share with the SQL Community the feedback of my PASS Summit 2010 Workshop. For those who were not there, my workshop was the “BI From A-Z” and the main objective of that workshop was to introduce people in the BI world not only from a technical point of view but insist a lot on the methodological and “engineered” approach. The will to put more engineering in the IT (and specially in the BI field) is something that has been growing stronger and stronger in me every day for of this last 5 years since is simply envy the fact that Airbus, Fincatieri, BMW (just to name a few) can create very complex machine “just” using putting people together and giving them some rules to follow (Of course this is an oversimplification but I think you get what I mean). The key point of engineering is that, after having defined the project blueprint, you have the possibility to give to a huge number of people, the rules to follow, the correct tools in order to implement the rules easily and semi-automatically and a way to measure the quality of the results. Could this be done in IT? Very big question, so my scope is now limited to BI. So that’s the main point of my workshop: and entry-level approach to BI (level was 200) in order to allow attendees to know the basics, to understand what tools they should use for which purpose and, above all, a set of rules and tools in order to make a BI solution scalable in terms of people working on it, while still maintaining a very good quality. All done not focusing only on the practice but explaining the theory behind to see how it can help *a lot* to build a correct solution despite the technology used to implement it. The idea is to reach a point where more then 70% of the work done to create a BI solution can be reused even if technologies changes. This is a very demanding challenge nowadays with the coming of Denali and its column-aligned storage and the shiny-new DAX language. As you may understand I was looking forward to get the feedback since you may have noticed that there’s a lot of “architectural” stuff in IT but really nothing on “engineering”. So how the session could be perceived by the attendees was really unknown to me. The feedback could also give a good indication if the need of more “engineering” is something I feel only by myself or if is something more broad. I’m very happy to be able to say that the overall score of 4.75 put my workshop in the TOP 20 session (on near 200 sessions)! Here’s the detailed evaluations: How would you rate the usefulness of the information presented in your day-to-day environment? 4.75 Answer:    # of Responses 3    1         4    12        5    42               How would you rate the Speaker's presentation skills? 4.80 Answer:    # of Responses 3 : 1         4 : 9         5 : 45               How would you rate the Speaker's knowledge of the subject? 4.95 Answer:    # of Responses 4 :  3         5 : 52               How would you rate the accuracy of the session title, description and experience level to the actual session? 4.75 Answer:    # of Responses 3 : 2         4 : 10         5 : 43               How would you rate the amount of time allocated to cover the topic/session? 4.44 Answer:    # of Responses 3 : 7         4 : 17        5 : 31               How would you rate the quality of the presentation materials? 4.62 Answer:    # of Responses 4 : 21        5 : 34 The comments where all very positive. Many of them asked for more time on the subject (or to shorten the very last topics). I’ll make treasure of these comments and will review the content accordingly. We’ll organize a two-day classes on this topic, where also more examples will be shown and some arguments will be explained more deeply. I’d just like to answer a comment that asks how much of what I shown is “universally applicable”. I can tell you that all of our BI project follow these rules and they’ve been applied to different markets (Insurance, Fashion, GDO) with different people and different teams and they allowed us to be “Adaptive” against the customer. The more the rules are well defined and the more there are tools that supports their implementations, the easier is to add new people to the project and to add or change solution features. Think of a car. How come that almost any mechanic can help you to fix a problem? Because they know what to expect. Because there a rules that allow them to identify the problem without having to discover each time how the car has been implemented build. And this is of course also true for car upgrades/improvements. Last but not least: thanks a lot to everyone for coming!

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• Handling TclErrors in Python

  - by anteater7171

  In the following code I'll get the following error if I right click the window that pops up. Then go down to the very bottom entry widget then delete it's contents. It seems to be giving me a TclError. How do I go about handeling such an error? The Error Exception in Tkinter callback Traceback (most recent call last): File "C:\Python26\Lib\lib-tk\Tkinter.py", line 1410, in __call__ return self.func(*args) File "C:\Python26\CPUDEMO.py", line 503, in I TL.sclS.set(S1) File "C:\Python26\Lib\lib-tk\Tkinter.py", line 2765, in set self.tk.call(self._w, 'set', value) TclError: expected floating-point number but got "" The Code #F #PIthon.py # Import/Setup import Tkinter import psutil,time import re from PIL import Image, ImageTk from time import sleep class simpleapp_tk(Tkinter.Tk): def __init__(self,parent): Tkinter.Tk.__init__(self,parent) self.parent = parent self.initialize() def initialize(self): Widgets self.menu = Tkinter.Menu(self, tearoff = 0 ) M = [ "Options...", "Exit"] self.selectedM = Tkinter.StringVar() self.menu.add_radiobutton( label = 'Hide', variable = self.selectedM, command = self.E ) self.menu.add_radiobutton( label = 'Bump', variable = self.selectedM, command = self.E ) self.menu.add_separator() self.menu.add_radiobutton( label = 'Options...', variable = self.selectedM, command = self.E ) self.menu.add_separator() self.menu.add_radiobutton( label = 'Exit', variable = self.selectedM, command = self.E ) self.frame1 = Tkinter.Frame(self,bg='grey15',relief='ridge',borderwidth=4,width=185, height=39) self.frame1.grid() self.frame1.grid_propagate(0) self.frame1.bind( "<Button-3><ButtonRelease-3>", self.D ) self.frame1.bind( "<Button-2><ButtonRelease-2>", self.C ) self.frame1.bind( "<Double-Button-1>", self.C ) self.labelVariable = Tkinter.StringVar() self.label = Tkinter.Label(self.frame1,textvariable=self.labelVariable,fg="lightgreen",bg="grey15",borderwidth=1,font=('arial', 10, 'bold')) self.label.grid(column=1,row=0,columnspan=1,sticky='nsew') self.label.bind( "<Button-3><ButtonRelease-3>", self.D ) self.label.bind( "<Button-2><ButtonRelease-2>", self.C ) self.label.bind( "<Double-Button-1>", self.C ) self.F() self.overrideredirect(1) self.wm_attributes("-topmost", 1) global TL1 TL1 = Tkinter.Toplevel(self) TL1.wm_geometry("+0+5000") TL1.overrideredirect(1) TL1.button = Tkinter.Button(TL1,text="? CPU",fg="lightgreen",bg="grey15",activeforeground="lightgreen", activebackground='grey15',borderwidth=4,font=('Arial', 8, 'bold'),command=self.J) TL1.button.pack(ipadx=1) Events def Reset(self): self.label.configure(font=('arial', 10, 'bold'),fg='Lightgreen',bg='grey15',borderwidth=0) self.labela.configure(font=('arial', 8, 'bold'),fg='Lightgreen',bg='grey15',borderwidth=0) self.frame1.configure(bg='grey15',relief='ridge',borderwidth=4,width=224, height=50) self.label.pack(ipadx=38) def helpmenu(self): t2 = Tkinter.Toplevel(self) Tkinter.Label(t2, text='This is a help menu', anchor="w",justify="left",fg="darkgreen",bg="grey90",relief="ridge",borderwidth=5,font=('Arial', 10)).pack(fill='both', expand=1) t2.resizable(False,False) t2.title('Help') menu = Tkinter.Menu(self) t2.config(menu=menu) filemenu = Tkinter.Menu(menu) menu.add_cascade(label="| Exit |", menu=filemenu) filemenu.add_command(label="Exit", command=t2.destroy) def aboutmenu(self): t1 = Tkinter.Toplevel(self) Tkinter.Label(t1, text=' About:\n\n CPU Usage v1.0\n\n Publisher: Drew French\n Date: 05/09/10\n Email: [email protected] \n\n\n\n\n\n\n Written in Python 2.6.4', anchor="w",justify="left",fg="darkgreen",bg="grey90",relief="sunken",borderwidth=5,font=('Arial', 10)).pack(fill='both', expand=1) t1.resizable(False,False) t1.title('About') menu = Tkinter.Menu(self) t1.config(menu=menu) filemenu = Tkinter.Menu(menu) menu.add_cascade(label="| Exit |", menu=filemenu) filemenu.add_command(label="Exit", command=t1.destroy) def A (self,event): TL.entryVariable1.set(TL.sclY.get()) TL.entryVariable2.set(TL.sclX.get()) Y = TL.sclY.get() X = TL.sclX.get() self.wm_geometry("+" + str(X) + "+" + str(Y)) def B(self,event): Y1 = TL.entryVariable1.get() X1 = TL.entryVariable2.get() self.wm_geometry("+" + str(X1) + "+" + str(Y1)) TL.sclY.set(Y1) TL.sclX.set(X1) def C(self,event): s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) - 150 P = M + 150 while Y3 > M: sleep(0.0009) Y3 = int(Y3) - 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) sleep(2.00) while Y3 < P: sleep(0.0009) Y3 = int(Y3) + 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) def D(self, event=None): self.menu.post( event.x_root, event.y_root ) def E(self): if self.selectedM.get() =='Options...': Setup global TL TL = Tkinter.Toplevel(self) menu = Tkinter.Menu(TL) TL.config(menu=menu) filemenu = Tkinter.Menu(menu) menu.add_cascade(label="| Menu |", menu=filemenu) filemenu.add_command(label="Instruction Manual...", command=self.helpmenu) filemenu.add_command(label="About...", command=self.aboutmenu) filemenu.add_separator() filemenu.add_command(label="Exit Options", command=TL.destroy) filemenu.add_command(label="Exit", command=self.destroy) helpmenu = Tkinter.Menu(menu) menu.add_cascade(label="| Help |", menu=helpmenu) helpmenu.add_command(label="Instruction Manual...", command=self.helpmenu) helpmenu.add_separator() helpmenu.add_command(label="Quick Help...", command=self.helpmenu) Title TL.label5 = Tkinter.Label(TL,text="CPU Usage: Options",anchor="center",fg="black",bg="lightgreen",relief="ridge",borderwidth=5,font=('Arial', 18, 'bold')) TL.label5.pack(padx=15,ipadx=5) X Y scale TL.separator = Tkinter.Frame(TL,height=7, bd=1, relief='ridge', bg='grey95') TL.separator.pack(pady=5,padx=5) # TL.sclX = Tkinter.Scale(TL.separator, from_=0, to=1500, orient='horizontal', resolution=1, command=self.A) TL.sclX.grid(column=1,row=0,ipadx=27, sticky='w') TL.label1 = Tkinter.Label(TL.separator,text="X",anchor="s",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label1.grid(column=0,row=0, pady=1, sticky='S') TL.sclY = Tkinter.Scale(TL.separator, from_=0, to=1500, resolution=1, command=self.A) TL.sclY.grid(column=2,row=1,rowspan=2,sticky='e', padx=4) TL.label3 = Tkinter.Label(TL.separator,text="Y",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label3.grid(column=2,row=0, padx=10, sticky='e') TL.entryVariable2 = Tkinter.StringVar() TL.entry2 = Tkinter.Entry(TL.separator,textvariable=TL.entryVariable2, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entry2.grid(column=1,row=1,ipadx=20, pady=10,sticky='EW') TL.entry2.bind("<Return>", self.B) TL.label2 = Tkinter.Label(TL.separator,text="X:",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label2.grid(column=0,row=1, ipadx=4, sticky='W') TL.entryVariable1 = Tkinter.StringVar() TL.entry1 = Tkinter.Entry(TL.separator,textvariable=TL.entryVariable1, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entry1.grid(column=1,row=2,sticky='EW') TL.entry1.bind("<Return>", self.B) TL.label4 = Tkinter.Label(TL.separator,text="Y:", anchor="center",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label4.grid(column=0,row=2, ipadx=4, sticky='W') TL.label7 = Tkinter.Label(TL.separator,text="Text Colour:",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label7.grid(column=1,row=3,stick="W",ipady=10) TL.selectedP = Tkinter.StringVar() TL.opt1 = Tkinter.OptionMenu(TL.separator, TL.selectedP,'Normal', 'White','Black', 'Blue', 'Steel Blue','Green','Light Green','Yellow','Orange' ,'Red',command=self.G) TL.opt1.config(fg="black",bg="grey90",activebackground="grey90",activeforeground="black", anchor="center",relief="raised",direction='right',font=('Arial', 10)) TL.opt1.grid(column=1,row=4,sticky='EW',padx=20,ipadx=20) TL.selectedP.set('Normal') TL.label7 = Tkinter.Label(TL.separator,text="Refresh Rate:",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label7.grid(column=1,row=5,stick="W",ipady=10) TL.sclS = Tkinter.Scale(TL.separator, from_=10, to=2000, orient='horizontal', resolution=10, command=self.H) TL.sclS.grid(column=1,row=6,ipadx=27, sticky='w') TL.sclS.set(650) TL.entryVariableS = Tkinter.StringVar() TL.entryS = Tkinter.Entry(TL.separator,textvariable=TL.entryVariableS, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entryS.grid(column=1,row=7,ipadx=20, pady=10,sticky='EW') TL.entryS.bind("<Return>", self.I) TL.entryVariableS.set(650) # TL.resizable(False,False) TL.title('Options') geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") s = self.wm_geometry() m = geomPatt.search(s) X = m.group(4) Y = m.group(6) TL.sclY.set(Y) TL.sclX.set(X) if self.selectedM.get() == 'Exit': self.destroy() if self.selectedM.get() == 'Bump': s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) - 150 P = M + 150 while Y3 > M: sleep(0.0009) Y3 = int(Y3) - 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) sleep(2.00) while Y3 < P: sleep(0.0009) Y3 = int(Y3) + 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) if self.selectedM.get() == 'Hide': s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) + 5000 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(M)) TL1.wm_geometry("+0+190") def F (self): G = round(psutil.cpu_percent(), 1) G1 = str(G) + '%' self.labelVariable.set(G1) try: S2 = TL.entryVariableS.get() except ValueError, e: S2 = 650 except NameError: S2 = 650 self.after(int(S2), self.F) def G (self,event): if TL.selectedP.get() =='Normal': self.label.config( fg = 'lightgreen' ) TL1.button.config( fg = 'lightgreen',activeforeground='lightgreen') if TL.selectedP.get() =='Red': self.label.config( fg = 'red' ) TL1.button.config( fg = 'red',activeforeground='red') if TL.selectedP.get() =='Orange': self.label.config( fg = 'orange') TL1.button.config( fg = 'orange',activeforeground='orange') if TL.selectedP.get() =='Yellow': self.label.config( fg = 'yellow') TL1.button.config( fg = 'yellow',activeforeground='yellow') if TL.selectedP.get() =='Light Green': self.label.config( fg = 'lightgreen' ) TL1.button.config( fg = 'lightgreen',activeforeground='lightgreen') if TL.selectedP.get() =='Normal': self.label.config( fg = 'lightgreen' ) TL1.button.config( fg = 'lightgreen',activeforeground='lightgreen') if TL.selectedP.get() =='Steel Blue': self.label.config( fg = 'steelblue1' ) TL1.button.config( fg = 'steelblue1',activeforeground='steelblue1') if TL.selectedP.get() =='Blue': self.label.config( fg = 'blue') TL1.button.config( fg = 'blue',activeforeground='blue') if TL.selectedP.get() =='Green': self.label.config( fg = 'darkgreen' ) TL1.button.config( fg = 'darkgreen',activeforeground='darkgreen') if TL.selectedP.get() =='White': self.label.config( fg = 'white' ) TL1.button.config( fg = 'white',activeforeground='white') if TL.selectedP.get() =='Black': self.label.config( fg = 'black') TL1.button.config( fg = 'black',activeforeground='black') def H (self,event): TL.entryVariableS.set(TL.sclS.get()) S = TL.sclS.get() def I (self,event): S1 = TL.entryVariableS.get() TL.sclS.set(S1) TL.sclS.set(TL.sclS.get()) S1 = TL.entryVariableS.get() TL.sclS.set(S1) def J (self): s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) - 5000 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(M)) TL1.wm_geometry("+0+5000") Loop if name == "main": app = simpleapp_tk(None) app.mainloop()

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• Will these optimizations to my Ruby implementation of diff improve performance in a Rails app?

  - by grg-n-sox

  <tl;dr> In source version control diff patch generation, would it be worth it to use the optimizations listed at the very bottom of this writing (see <optimizations>) in my Ruby implementation of diff for making diff patches? </tl;dr> <introduction> I am programming something I have never done before and there might already be tools out there to do the exact thing I am programming but at this point I am having too much fun to care so I am still going to do it from scratch, even if there is a tool for this. So anyways, I am working on a Ruby on Rails app and need a certain feature. Basically I want each entry in a table of mine, let's say for example a table of video games, to have a stored chunk of text that represents a review or something of the sort for that table entry. However, I want this text to be both editable by any registered user and also keep track of different submissions in a version control system. The simplest solution I could think of is just implement a solution that keeps track of the text body and the diff patch history of different versions of the text body as objects in Ruby and then serialize it, preferably in human readable form (so I'll most likely use YAML for this) for editing if needed due to corruption by a software bug or a mistake is made by an admin doing some version editing. So at first I just tried to dive in head first into this feature to find that the problem of generating a diff patch is more difficult that I thought to do efficiently. So I did some research and came across some ideas. Some I have implemented already and some I have not. However, it all pretty much revolves around the longest common subsequence problem, as you would already know if you have already done anything with diff or diff-like features, and optimization the function that solves it. Currently I have it so it truncates the compared versions of the text body from the beginning and end until non-matching lines are found. Then it solves the problem using a comparison matrix, but instead of incrementing the value stored in a cell when it finds a matching line like in most longest common subsequence algorithms I have seen examples of, I increment when I have a non-matching line so as to calculate edit distance instead of longest common subsequence. Although as far as I can tell between the two approaches, they are essentially two sides of the same coin so either could be used to derive an answer. It then back-traces through the comparison matrix and notes when there was an incrementation and in which adjacent cell (West, Northwest, or North) to determine that line's diff entry and assumes all other lines to be unchanged. Normally I would leave it at that, but since this is going into a Rails environment and not just some stand-alone Ruby script, I started getting worried about needing to optimize at least enough so if a spammer that somehow knew how I implemented the version control system and knew my worst case scenario entry still wouldn't be able to hit the server that bad. After some searching and reading of research papers and articles through the internet, I've come across several that seem decent but all seem to have pros and cons and I am having a hard time deciding how well in this situation that the pros and cons balance out. So are the ones listed here worth it? I have listed them with known pros and cons. </introduction> <optimizations> Chop the compared sequences into multiple chucks of subsequences by splitting where lines are unchanged, and then truncating each section of unchanged lines at the beginning and end of each section. Then solve the edit distance of each subsequence. Pro: Changes the time increase as the changed area gets bigger from a quadratic increase to something more similar to a linear increase. Con: Figuring out where to split already seems like you have to solve edit distance except now you don't care how it is changed. Would be fine if this was solvable by a process closer to solving hamming distance but a single insertion would throw this off. Use a cryptographic hash function to both convert all sequence elements into integers and ensure uniqueness. Then solve the edit distance comparing the hash integers instead of the sequence elements themselves. Pro: The operation of comparing two integers is faster than the operation of comparing two strings, so a slight performance gain is received after every comparison, which can be a lot overall. Con: Using a cryptographic hash function takes time to convert all the sequence elements and may end up costing more time to do the conversion that you gain back from the integer comparisons. You could use the built in hash function for a string but that will not guarantee uniqueness. Use lazy evaluation to only calculate the three center-most diagonals of the comparison matrix and then only calculate additional diagonals as needed. And then also use this approach to possibly remove the need on some comparisons to compare all three adjacent cells as desribed here. Pro: Can turn an algorithm that always takes O(n * m) time and make it so only worst case scenario is that time, best case becomes practically linear, and average case is somewhere between the two. Con: It is an algorithm I've only seen implemented in functional programming languages and I am having a difficult time comprehending how to convert this into Ruby based on how it is described at the site linked to above. Make a C module and do the hard work at the native level in C and just make a Ruby wrapper for it so Ruby can make all the calls to it that it needs. Pro: I have to imagine that evaluating something like this in could be a LOT faster. Con: I have no idea how Rails handles apps with ruby code that has C extensions and it hurts the portability of the app. This is an optimization for after the solving of edit distance, but idea is to store additional combined diffs with the ones produced by each version to make a delta-tree data structure with the most recently made diff as the root node of the tree so getting to any version takes worst case time of O(log n) instead of O(n). Pro: Would make going back to an old version a lot faster. Con: It would mean every new commit, the delta-tree would get a new root node that will cost time to reorganize the delta-tree for an operation that will be carried out a lot more often than going back a version, not to mention the unlikelihood it will be an old version. </optimizations> So are these things worth the effort?

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• Azure Diagnostics wrt Custom Logs and honoring scheduledTransferPeriod

  - by kjsteuer

  I have implemented my own TraceListener similar to http://blogs.technet.com/b/meamcs/archive/2013/05/23/diagnostics-of-cloud-services-custom-trace-listener.aspx . One thing I noticed is that that logs show up immediately in My Azure Table Storage. I wonder if this is expected with Custom Trace Listeners or because I am in a development environment. My diagnosics.wadcfg <?xml version="1.0" encoding="utf-8"?> <DiagnosticMonitorConfiguration configurationChangePollInterval="PT1M""overallQuotaInMB="4096" xmlns="http://schemas.microsoft.com/ServiceHosting/2010/10/DiagnosticsConfiguration"> <DiagnosticInfrastructureLogs scheduledTransferLogLevelFilter="Information" /> <Directories scheduledTransferPeriod="PT1M"> <IISLogs container="wad-iis-logfiles" /> <CrashDumps container="wad-crash-dumps" /> </Directories> <Logs bufferQuotaInMB="0" scheduledTransferPeriod="PT30M" scheduledTransferLogLevelFilter="Information" /> </DiagnosticMonitorConfiguration> I have changed my approach a bit. Now I am defining in the web config of my webrole. I notice when I set autoflush to true in the webconfig, every thing works but scheduledTransferPeriod is not honored because the flush method pushes to the table storage. I would like to have scheduleTransferPeriod trigger the flush or trigger flush after a certain number of log entries like the buffer is full. Then I can also flush on server shutdown. Is there any method or event on the CustomTraceListener where I can listen to the scheduleTransferPeriod? <system.diagnostics> <!--http://msdn.microsoft.com/en-us/library/sk36c28t(v=vs.110).aspx By default autoflush is false. By default useGlobalLock is true. While we try to be threadsafe, we keep this default for now. Later if we would like to increase performance we can remove this. see http://msdn.microsoft.com/en-us/library/system.diagnostics.trace.usegloballock(v=vs.110).aspx --> <trace> <listeners> <add name="TableTraceListener" type="Pos.Services.Implementation.TableTraceListener, Pos.Services.Implementation" /> <remove name="Default" /> </listeners> </trace> </system.diagnostics> I have modified the custom trace listener to the following: namespace Pos.Services.Implementation { class TableTraceListener : TraceListener { #region Fields //connection string for azure storage readonly string _connectionString; //Custom sql storage table for logs. //TODO put in config readonly string _diagnosticsTable; [ThreadStatic] static StringBuilder _messageBuffer; readonly object _initializationSection = new object(); bool _isInitialized; CloudTableClient _tableStorage; readonly object _traceLogAccess = new object(); readonly List<LogEntry> _traceLog = new List<LogEntry>(); #endregion #region Constructors public TableTraceListener() : base("TableTraceListener") { _connectionString = RoleEnvironment.GetConfigurationSettingValue("DiagConnection"); _diagnosticsTable = RoleEnvironment.GetConfigurationSettingValue("DiagTableName"); } #endregion #region Methods /// <summary> /// Flushes the entries to the storage table /// </summary> public override void Flush() { if (!_isInitialized) { lock (_initializationSection) { if (!_isInitialized) { Initialize(); } } } var context = _tableStorage.GetTableServiceContext(); context.MergeOption = MergeOption.AppendOnly; lock (_traceLogAccess) { _traceLog.ForEach(entry => context.AddObject(_diagnosticsTable, entry)); _traceLog.Clear(); } if (context.Entities.Count > 0) { context.BeginSaveChangesWithRetries(SaveChangesOptions.None, (ar) => context.EndSaveChangesWithRetries(ar), null); } } /// <summary> /// Creates the storage table object. This class does not need to be locked because the caller is locked. /// </summary> private void Initialize() { var account = CloudStorageAccount.Parse(_connectionString); _tableStorage = account.CreateCloudTableClient(); _tableStorage.GetTableReference(_diagnosticsTable).CreateIfNotExists(); _isInitialized = true; } public override bool IsThreadSafe { get { return true; } } #region Trace and Write Methods /// <summary> /// Writes the message to a string buffer /// </summary> /// <param name="message">the Message</param> public override void Write(string message) { if (_messageBuffer == null) _messageBuffer = new StringBuilder(); _messageBuffer.Append(message); } /// <summary> /// Writes the message with a line breaker to a string buffer /// </summary> /// <param name="message"></param> public override void WriteLine(string message) { if (_messageBuffer == null) _messageBuffer = new StringBuilder(); _messageBuffer.AppendLine(message); } /// <summary> /// Appends the trace information and message /// </summary> /// <param name="eventCache">the Event Cache</param> /// <param name="source">the Source</param> /// <param name="eventType">the Event Type</param> /// <param name="id">the Id</param> /// <param name="message">the Message</param> public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string message) { base.TraceEvent(eventCache, source, eventType, id, message); AppendEntry(id, eventType, eventCache); } /// <summary> /// Adds the trace information to a collection of LogEntry objects /// </summary> /// <param name="id">the Id</param> /// <param name="eventType">the Event Type</param> /// <param name="eventCache">the EventCache</param> private void AppendEntry(int id, TraceEventType eventType, TraceEventCache eventCache) { if (_messageBuffer == null) _messageBuffer = new StringBuilder(); var message = _messageBuffer.ToString(); _messageBuffer.Length = 0; if (message.EndsWith(Environment.NewLine)) message = message.Substring(0, message.Length - Environment.NewLine.Length); if (message.Length == 0) return; var entry = new LogEntry() { PartitionKey = string.Format("{0:D10}", eventCache.Timestamp >> 30), RowKey = string.Format("{0:D19}", eventCache.Timestamp), EventTickCount = eventCache.Timestamp, Level = (int)eventType, EventId = id, Pid = eventCache.ProcessId, Tid = eventCache.ThreadId, Message = message }; lock (_traceLogAccess) _traceLog.Add(entry); } #endregion #endregion } }

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• How do I get my dependenices inject using @Configurable in conjunction with readResolve()

  - by bmatthews68

  The framework I am developing for my application relies very heavily on dynamically generated domain objects. I recently started using Spring WebFlow and now need to be able to serialize my domain objects that will be kept in flow scope. I have done a bit of research and figured out that I can use writeReplace() and readResolve(). The only catch is that I need to look-up a factory in the Spring context. I tried to use @Configurable(preConstruction = true) in conjunction with the BeanFactoryAware marker interface. But beanFactory is always null when I try to use it in my createEntity() method. Neither the default constructor nor the setBeanFactory() injector are called. Has anybody tried this or something similar? I have included relevant class below. Thanks in advance, Brian /* * Copyright 2008 Brian Thomas Matthews Limited. * All rights reserved, worldwide. * * This software and all information contained herein is the property of * Brian Thomas Matthews Limited. Any dissemination, disclosure, use, or * reproduction of this material for any reason inconsistent with the * express purpose for which it has been disclosed is strictly forbidden. */ package com.btmatthews.dmf.domain.impl.cglib; import java.io.InvalidObjectException; import java.io.ObjectStreamException; import java.io.Serializable; import java.lang.reflect.InvocationTargetException; import java.util.HashMap; import java.util.Map; import org.apache.commons.beanutils.PropertyUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.BeanFactory; import org.springframework.beans.factory.BeanFactoryAware; import org.springframework.beans.factory.annotation.Configurable; import org.springframework.util.StringUtils; import com.btmatthews.dmf.domain.IEntity; import com.btmatthews.dmf.domain.IEntityFactory; import com.btmatthews.dmf.domain.IEntityID; import com.btmatthews.dmf.spring.IEntityDefinitionBean; /** * This class represents the serialized form of a domain object implemented * using CGLib. The readResolve() method recreates the actual domain object * after it has been deserialized into Serializable. You must define * &lt;spring-configured/&gt; in the application context. * * @param <S> * The interface that defines the properties of the base domain * object. * @param <T> * The interface that defines the properties of the derived domain * object. * @author <a href="mailto:[email protected]">Brian Matthews</a> * @version 1.0 */ @Configurable(preConstruction = true) public final class SerializedCGLibEntity<S extends IEntity<S>, T extends S> implements Serializable, BeanFactoryAware { /** * Used for logging. */ private static final Logger LOG = LoggerFactory .getLogger(SerializedCGLibEntity.class); /** * The serialization version number. */ private static final long serialVersionUID = 3830830321957878319L; /** * The application context. Note this is not serialized. */ private transient BeanFactory beanFactory; /** * The domain object name. */ private String entityName; /** * The domain object identifier. */ private IEntityID<S> entityId; /** * The domain object version number. */ private long entityVersion; /** * The attributes of the domain object. */ private HashMap<?, ?> entityAttributes; /** * The default constructor. */ public SerializedCGLibEntity() { SerializedCGLibEntity.LOG .debug("Initializing with default constructor"); } /** * Initialise with the attributes to be serialised. * * @param name * The entity name. * @param id * The domain object identifier. * @param version * The entity version. * @param attributes * The entity attributes. */ public SerializedCGLibEntity(final String name, final IEntityID<S> id, final long version, final HashMap<?, ?> attributes) { SerializedCGLibEntity.LOG .debug("Initializing with parameterized constructor"); this.entityName = name; this.entityId = id; this.entityVersion = version; this.entityAttributes = attributes; } /** * Inject the bean factory. * * @param factory * The bean factory. */ public void setBeanFactory(final BeanFactory factory) { SerializedCGLibEntity.LOG.debug("Injected bean factory"); this.beanFactory = factory; } /** * Called after deserialisation. The corresponding entity factory is * retrieved from the bean application context and BeanUtils methods are * used to initialise the object. * * @return The initialised domain object. * @throws ObjectStreamException * If there was a problem creating or initialising the domain * object. */ public Object readResolve() throws ObjectStreamException { SerializedCGLibEntity.LOG.debug("Transforming deserialized object"); final T entity = this.createEntity(); entity.setId(this.entityId); try { PropertyUtils.setSimpleProperty(entity, "version", this.entityVersion); for (Map.Entry<?, ?> entry : this.entityAttributes.entrySet()) { PropertyUtils.setSimpleProperty(entity, entry.getKey() .toString(), entry.getValue()); } } catch (IllegalAccessException e) { throw new InvalidObjectException(e.getMessage()); } catch (InvocationTargetException e) { throw new InvalidObjectException(e.getMessage()); } catch (NoSuchMethodException e) { throw new InvalidObjectException(e.getMessage()); } return entity; } /** * Lookup the entity factory in the application context and create an * instance of the entity. The entity factory is located by getting the * entity definition bean and using the factory registered with it or * getting the entity factory. The name used for the definition bean lookup * is ${entityName}Definition while ${entityName} is used for the factory * lookup. * * @return The domain object instance. * @throws ObjectStreamException * If the entity definition bean or entity factory were not * available. */ @SuppressWarnings("unchecked") private T createEntity() throws ObjectStreamException { SerializedCGLibEntity.LOG.debug("Getting domain object factory"); // Try to use the entity definition bean final IEntityDefinitionBean<S, T> entityDefinition = (IEntityDefinitionBean<S, T>)this.beanFactory .getBean(StringUtils.uncapitalize(this.entityName) + "Definition", IEntityDefinitionBean.class); if (entityDefinition != null) { final IEntityFactory<S, T> entityFactory = entityDefinition .getFactory(); if (entityFactory != null) { SerializedCGLibEntity.LOG .debug("Domain object factory obtained via enity definition bean"); return entityFactory.create(); } } // Try to use the entity factory final IEntityFactory<S, T> entityFactory = (IEntityFactory<S, T>)this.beanFactory .getBean(StringUtils.uncapitalize(this.entityName) + "Factory", IEntityFactory.class); if (entityFactory != null) { SerializedCGLibEntity.LOG .debug("Domain object factory obtained via direct look-up"); return entityFactory.create(); } // Neither worked! SerializedCGLibEntity.LOG.warn("Cannot find domain object factory"); throw new InvalidObjectException( "No entity definition or factory found for " + this.entityName); } }

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• Uploading multiple files using Spring MVC 3.0.2 after HiddenHttpMethodFilter has been enabled

  - by Tiny

  I'm using Spring version 3.0.2. I need to upload multiple files using the multiple="multiple" attribute of a file browser such as, <input type="file" id="myFile" name="myFile" multiple="multiple"/> (and not using multiple file browsers something like the one stated by this answer, it indeed works I tried). Although no versions of Internet Explorer supports this approach unless an appropriate jQuery plugin/widget is used, I don't care about it right now (since most other browsers support this). This works fine with commons fileupload but in addition to using RequestMethod.POST and RequestMethod.GET methods, I also want to use other request methods supported and suggested by Spring like RequestMethod.PUT and RequestMethod.DELETE in their own appropriate places. For this to be so, I have configured Spring with HiddenHttpMethodFilter which goes fine as this question indicates. but it can upload only one file at a time even though multiple files in the file browser are chosen. In the Spring controller class, a method is mapped as follows. @RequestMapping(method={RequestMethod.POST}, value={"admin_side/Temp"}) public String onSubmit(@RequestParam("myFile") List<MultipartFile> files, @ModelAttribute("tempBean") TempBean tempBean, BindingResult error, Map model, HttpServletRequest request, HttpServletResponse response) throws IOException, FileUploadException { for(MultipartFile file:files) { System.out.println(file.getOriginalFilename()); } } Even with the request parameter @RequestParam("myFile") List<MultipartFile> files which is a List of type MultipartFile (it can always have only one file at a time). I could find a strategy which is likely to work with multiple files on this blog. I have gone through it carefully. The solution below the section SOLUTION 2 – USE THE RAW REQUEST says, If however the client insists on using the same form input name such as ‘files[]‘ or ‘files’ and then populating that name with multiple files then a small hack is necessary as follows. As noted above Spring 2.5 throws an exception if it detects the same form input name of type file more than once. CommonsFileUploadSupport – the class which throws that exception is not final and the method which throws that exception is protected so using the wonders of inheritance and subclassing one can simply fix/modify the logic a little bit as follows. The change I’ve made is literally one word representing one method invocation which enables us to have multiple files incoming under the same form input name. It attempts to override the method protected MultipartParsingResult parseFileItems(List fileItems, String encoding) {} of the abstract class CommonsFileUploadSupport by extending the class CommonsMultipartResolver such as, package multipartResolver; import java.io.UnsupportedEncodingException; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import javax.servlet.ServletContext; import org.apache.commons.fileupload.FileItem; import org.springframework.util.StringUtils; import org.springframework.web.multipart.MultipartException; import org.springframework.web.multipart.MultipartFile; import org.springframework.web.multipart.commons.CommonsMultipartFile; import org.springframework.web.multipart.commons.CommonsMultipartResolver; final public class MultiCommonsMultipartResolver extends CommonsMultipartResolver { public MultiCommonsMultipartResolver() { } public MultiCommonsMultipartResolver(ServletContext servletContext) { super(servletContext); } @Override @SuppressWarnings("unchecked") protected MultipartParsingResult parseFileItems(List fileItems, String encoding) { Map<String, MultipartFile> multipartFiles = new HashMap<String, MultipartFile>(); Map multipartParameters = new HashMap(); // Extract multipart files and multipart parameters. for (Iterator it = fileItems.iterator(); it.hasNext();) { FileItem fileItem = (FileItem) it.next(); if (fileItem.isFormField()) { String value = null; if (encoding != null) { try { value = fileItem.getString(encoding); } catch (UnsupportedEncodingException ex) { if (logger.isWarnEnabled()) { logger.warn("Could not decode multipart item '" + fileItem.getFieldName() + "' with encoding '" + encoding + "': using platform default"); } value = fileItem.getString(); } } else { value = fileItem.getString(); } String[] curParam = (String[]) multipartParameters.get(fileItem.getFieldName()); if (curParam == null) { // simple form field multipartParameters.put(fileItem.getFieldName(), new String[] { value }); } else { // array of simple form fields String[] newParam = StringUtils.addStringToArray(curParam, value); multipartParameters.put(fileItem.getFieldName(), newParam); } } else { // multipart file field CommonsMultipartFile file = new CommonsMultipartFile(fileItem); if (multipartFiles.put(fileItem.getName(), file) != null) { throw new MultipartException("Multiple files for field name [" + file.getName() + "] found - not supported by MultipartResolver"); } if (logger.isDebugEnabled()) { logger.debug("Found multipart file [" + file.getName() + "] of size " + file.getSize() + " bytes with original filename [" + file.getOriginalFilename() + "], stored " + file.getStorageDescription()); } } } return new MultipartParsingResult(multipartFiles, multipartParameters); } } What happens is that the last line in the method parseFileItems() (the return statement) i.e. return new MultipartParsingResult(multipartFiles, multipartParameters); causes a compile-time error because the first parameter multipartFiles is a type of Map implemented by HashMap but in reality, it requires a parameter of type MultiValueMap<String, MultipartFile> It is a constructor of a static class inside the abstract class CommonsFileUploadSupport, public abstract class CommonsFileUploadSupport { protected static class MultipartParsingResult { public MultipartParsingResult(MultiValueMap<String, MultipartFile> mpFiles, Map<String, String[]> mpParams) { } } } The reason might be - this solution is about the Spring version 2.5 and I'm using the Spring version 3.0.2 which might be inappropriate for this version. I however tried to replace the Map with MultiValueMap in various ways such as the one shown in the following segment of code, MultiValueMap<String, MultipartFile>mul=new LinkedMultiValueMap<String, MultipartFile>(); for(Entry<String, MultipartFile>entry:multipartFiles.entrySet()) { mul.add(entry.getKey(), entry.getValue()); } return new MultipartParsingResult(mul, multipartParameters); but no success. I'm not sure how to replace Map with MultiValueMap and even doing so could work either. After doing this, the browser shows the Http response, HTTP Status 400 - type Status report message description The request sent by the client was syntactically incorrect (). Apache Tomcat/6.0.26 I have tried to shorten the question as possible as I could and I haven't included unnecessary code. How could be made it possible to upload multiple files after Spring has been configured with HiddenHttpMethodFilter? That blog indicates that It is a long standing, high priority bug. If there is no solution regarding the version 3.0.2 (3 or higher) then I have to disable Spring support forever and continue to use commons-fileupolad as suggested by the third solution on that blog omitting the PUT, DELETE and other request methods forever. Just curiously waiting for a solution and/or suggestion. Very little changes to the code in the parseFileItems() method inside the class MultiCommonsMultipartResolver might make it to upload multiple files but I couldn't succeed in my attempts (again with the Spring version 3.0.2 (3 or higher)).

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• Program crashes when item selected from listView

  - by philip

  The application just crash every time I try to click from the list. ListMovingNames.java public class ListMovingNames extends Activity { ListView MoveList; SQLHandler SQLHandlerview; Cursor cursor; Button addMove; EditText etAddMove; TextView temp; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.selectorcreatemove); addMove = (Button) findViewById(R.id.bAddMove); etAddMove = (EditText) findViewById(R.id.etMoveName); temp = (TextView) findViewById(R.id.tvTemp); MoveList = (ListView) findViewById(R.id.lvMoveItems); SQLHandlerview = new SQLHandler(this); SQLHandlerview = new SQLHandler(ListMovingNames.this); SQLHandlerview.open(); cursor = SQLHandlerview.getMove(); startManagingCursor(cursor); String[] from = new String[]{SQLHandler.KEY_MOVENAME}; int[] to = new int[]{R.id.text}; SimpleCursorAdapter cursorAdapter = new SimpleCursorAdapter(this, R.layout.row, cursor, from, to); MoveList.setAdapter(cursorAdapter); SQLHandlerview.close(); addMove.setOnClickListener(new OnClickListener() { public void onClick(View v) { // TODO Auto-generated method stub try { String ssmoveName = etAddMove.getText().toString(); SQLHandler entry = new SQLHandler(ListMovingNames.this); entry.open(); entry.createMove(ssmoveName); entry.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }); MoveList.setOnItemClickListener(new OnItemClickListener() { @SuppressLint("ShowToast") public void onItemClick(AdapterView<?> arg0, View view, int position, long id) { // TODO Auto-generated method stub // String moveset = cursor.getString(position); // temp.setText(moveset); Toast.makeText(ListMovingNames.this, position, Toast.LENGTH_SHORT); } }); } } and here's my database handler. But I'm sure that there's nothing wrong with it, its probably the cursor adapter. SQLHandler.java public class SQLHandler { public static final String KEY_ROOMMOVEHOLDER = "roommoveholder"; public static final String KEY_ROOM = "room"; public static final String KEY_ITEMMOVEHOLDER = "itemmoveholder"; public static final String KEY_ITEMNAME = "itemname"; public static final String KEY_ITEMVALUE = "itemvalue"; public static final String KEY_ROOMHOLDER = "roomholder"; public static final String KEY_MOVENAME = "movename"; public static final String KEY_ID1 = "_id"; public static final String KEY_ID2 = "_id"; public static final String KEY_ID3 = "_id"; public static final String KEY_ID4 = "_id"; public static final String KEY_MOVEDATE = "movedate"; private static final String DATABASE_NAME = "mymovingfriend"; private static final int DATABASE_VERSION = 1; public static final String KEY_SORTANDPURGE = "sortandpurge"; public static final String KEY_RESEARCH = "research"; public static final String KEY_CREATEMOVINGBINDER = "createmovingbinder"; public static final String KEY_ORDERSUPPLIES = "ordersupplies"; public static final String KEY_USEITORLOSEIT = "useitorloseit"; public static final String KEY_TAKEMEASUREMENTS = "takemeasurements"; public static final String KEY_CHOOSEMOVER = "choosemover"; public static final String KEY_BEGINPACKING = "beginpacking"; public static final String KEY_LABEL = "label"; public static final String KEY_SEPARATEVALUES = "separatevalues"; public static final String KEY_DOACHANGEOFADDRESS = "doachangeofaddress"; public static final String KEY_NOTIFYIMPORTANTPARTIES = "notifyimportantparties"; private static final String DATABASE_TABLE1 = "movingname"; private static final String DATABASE_TABLE2 = "movingrooms"; private static final String DATABASE_TABLE3 = "movingitems"; private static final String DATABASE_TABLE4 = "todolist"; public static final String CREATE_TABLE_1 = "CREATE TABLE " + DATABASE_TABLE1 + " (" + KEY_ID1 + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_MOVEDATE + " TEXT NOT NULL, " + KEY_MOVENAME + " TEXT NOT NULL);"; public static final String CREATE_TABLE_2 = "CREATE TABLE " + DATABASE_TABLE2 + " (" + KEY_ID2 + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_ROOMMOVEHOLDER + " TEXT NOT NULL, " + KEY_ROOM + " TEXT NOT NULL);"; public static final String CREATE_TABLE_3 = "CREATE TABLE " + DATABASE_TABLE3 + " (" + KEY_ID3 + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_ITEMNAME + " TEXT NOT NULL, " + KEY_ITEMVALUE + " TEXT NOT NULL, " + KEY_ROOMHOLDER + " TEXT NOT NULL, " + KEY_ITEMMOVEHOLDER + " TEXT NOT NULL);"; public static final String CREATE_TABLE_4 = "CREATE TABLE " + DATABASE_TABLE4 + " (" + KEY_ID4 + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_SORTANDPURGE + " TEXT NOT NULL, " + KEY_RESEARCH + " INTEGER NOT NULL, " + KEY_CREATEMOVINGBINDER + " TEXT NOT NULL, " + KEY_ORDERSUPPLIES + " TEXT NOT NULL, " + KEY_USEITORLOSEIT + " TEXT NOT NULL, " + KEY_TAKEMEASUREMENTS + " TEXT NOT NULL, " + KEY_CHOOSEMOVER + " TEXT NOT NULL, " + KEY_BEGINPACKING + " TEXT NOT NULL, " + KEY_LABEL + " TEXT NOT NULL, " + KEY_SEPARATEVALUES + " TEXT NOT NULL, " + KEY_DOACHANGEOFADDRESS + " TEXT NOT NULL, " + KEY_NOTIFYIMPORTANTPARTIES + " TEXT NOT NULL);"; private DbHelper ourHelper; private final Context ourContext; private SQLiteDatabase ourDatabase; private static class DbHelper extends SQLiteOpenHelper{ public DbHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); // TODO Auto-generated constructor stub } @Override public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub db.execSQL(CREATE_TABLE_1); db.execSQL(CREATE_TABLE_2); db.execSQL(CREATE_TABLE_3); db.execSQL(CREATE_TABLE_4); } @Override public void onUpgrade(SQLiteDatabase db, int oldversion, int newversion) { // TODO Auto-generated method stub db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE1); db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE2); db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE3); db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE4); onCreate(db); } } public SQLHandler(Context c){ ourContext = c; } public SQLHandler open() throws SQLException{ ourHelper = new DbHelper(ourContext); ourDatabase = ourHelper.getWritableDatabase(); return this; } public void close(){ ourHelper.close(); } public long createMove(String smovename){ ContentValues cv = new ContentValues(); cv.put(KEY_MOVENAME, smovename); cv.put(KEY_MOVEDATE, "Not yet set"); return ourDatabase.insert(DATABASE_TABLE1, null, cv); } public long addRooms(String sroommoveholder, String sroom){ ContentValues cv = new ContentValues(); cv.put(KEY_ROOMMOVEHOLDER, sroommoveholder); cv.put(KEY_ROOM, sroom); return ourDatabase.insert(DATABASE_TABLE2, null, cv); } public long addItems(String sitemmoveholder, String sroomholder, String sitemname, String sitemvalue){ ContentValues cv = new ContentValues(); cv.put(KEY_ITEMMOVEHOLDER, sitemmoveholder); cv.put(KEY_ROOMHOLDER, sroomholder); cv.put(KEY_ITEMNAME, sitemname); cv.put(KEY_ITEMVALUE, sitemvalue); return ourDatabase.insert(DATABASE_TABLE3, null, cv); } public long todoList(String todoitem){ ContentValues cv = new ContentValues(); cv.put(todoitem, "Done"); return ourDatabase.insert(DATABASE_TABLE4, null, cv); } public Cursor getMove(){ String[] columns = new String[]{KEY_ID1, KEY_MOVENAME}; Cursor cursor = ourDatabase.query(DATABASE_TABLE1, columns, null, null, null, null, null); return cursor; } } can anyone point out what I'm doing wrong? here's the log 09-19 03:22:36.596: E/AndroidRuntime(679): FATAL EXCEPTION: main 09-19 03:22:36.596: E/AndroidRuntime(679): android.content.res.Resources$NotFoundException: String resource ID #0x0 09-19 03:22:36.596: E/AndroidRuntime(679): at android.content.res.Resources.getText(Resources.java:201) 09-19 03:22:36.596: E/AndroidRuntime(679): at android.widget.Toast.makeText(Toast.java:258) 09-19 03:22:36.596: E/AndroidRuntime(679): at standard.internet.marketing.mymovingfriend.ListMovingNames$2.onItemClick(ListMovingNames.java:78) 09-19 03:22:36.596: E/AndroidRuntime(679): at android.widget.AdapterView.performItemClick(AdapterView.java:284) 09-19 03:22:36.596: E/AndroidRuntime(679): at android.widget.ListView.performItemClick(ListView.java:3382) 09-19 03:22:36.596: E/AndroidRuntime(679): at android.widget.AbsListView$PerformClick.run(AbsListView.java:1696) 09-19 03:22:36.596: E/AndroidRuntime(679): at android.os.Handler.handleCallback(Handler.java:587) 09-19 03:22:36.596: E/AndroidRuntime(679): at android.os.Handler.dispatchMessage(Handler.java:92) 09-19 03:22:36.596: E/AndroidRuntime(679): at android.os.Looper.loop(Looper.java:123) 09-19 03:22:36.596: E/AndroidRuntime(679): at android.app.ActivityThread.main(ActivityThread.java:4627) 09-19 03:22:36.596: E/AndroidRuntime(679): at java.lang.reflect.Method.invokeNative(Native Method) 09-19 03:22:36.596: E/AndroidRuntime(679): at java.lang.reflect.Method.invoke(Method.java:521) 09-19 03:22:36.596: E/AndroidRuntime(679): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 09-19 03:22:36.596: E/AndroidRuntime(679): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 09-19 03:22:36.596: E/AndroidRuntime(679): at dalvik.system.NativeStart.main(Native Method)

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• Using HTML 5 SessionState to save rendered Page Content

  - by Rick Strahl

  HTML 5 SessionState and LocalStorage are very useful and super easy to use to manage client side state. For building rich client side or SPA style applications it's a vital feature to be able to cache user data as well as HTML content in order to swap pages in and out of the browser's DOM. What might not be so obvious is that you can also use the sessionState and localStorage objects even in classic server rendered HTML applications to provide caching features between pages. These APIs have been around for a long time and are supported by most relatively modern browsers and even all the way back to IE8, so you can use them safely in your Web applications. SessionState and LocalStorage are easy The APIs that make up sessionState and localStorage are very simple. Both object feature the same API interface which  is a simple, string based key value store that has getItem, setItem, removeitem, clear and  key methods. The objects are also pseudo array objects and so can be iterated like an array with  a length property and you have array indexers to set and get values with. Basic usage  for storing and retrieval looks like this (using sessionStorage, but the syntax is the same for localStorage - just switch the objects):// set var lastAccess = new Date().getTime(); if (sessionStorage) sessionStorage.setItem("myapp_time", lastAccess.toString()); // retrieve in another page or on a refresh var time = null; if (sessionStorage) time = sessionStorage.getItem("myapp_time"); if (time) time = new Date(time * 1); else time = new Date(); sessionState stores data that is browser session specific and that has a liftetime of the active browser session or window. Shut down the browser or tab and the storage goes away. localStorage uses the same API interface, but the lifetime of the data is permanently stored in the browsers storage area until deleted via code or by clearing out browser cookies (not the cache). Both sessionStorage and localStorage space is limited. The spec is ambiguous about this - supposedly sessionStorage should allow for unlimited size, but it appears that most WebKit browsers support only 2.5mb for either object. This means you have to be careful what you store especially since other applications might be running on the same domain and also use the storage mechanisms. That said 2.5mb worth of character data is quite a bit and would go a long way. The easiest way to get a feel for how sessionState and localStorage work is to look at a simple example. You can go check out the following example online in Plunker: http://plnkr.co/edit/0ICotzkoPjHaWa70GlRZ?p=preview which looks like this: Plunker is an online HTML/JavaScript editor that lets you write and run Javascript code and similar to JsFiddle, but a bit cleaner to work in IMHO (thanks to John Papa for turning me on to it). The sample has two text boxes with counts that update session/local storage every time you click the related button. The counts are 'cached' in Session and Local storage. The point of these examples is that both counters survive full page reloads, and the LocalStorage counter survives a complete browser shutdown and restart. Go ahead and try it out by clicking the Reload button after updating both counters and then shutting down the browser completely and going back to the same URL (with the same browser). What you should see is that reloads leave both counters intact at the counted values, while a browser restart will leave only the local storage counter intact. The code to deal with the SessionStorage (and LocalStorage not shown here) in the example is isolated into a couple of wrapper methods to simplify the code: function getSessionCount() { var count = 0; if (sessionStorage) { var count = sessionStorage.getItem("ss_count"); count = !count ? 0 : count * 1; } $("#txtSession").val(count); return count; } function setSessionCount(count) { if (sessionStorage) sessionStorage.setItem("ss_count", count.toString()); } These two functions essentially load and store a session counter value. The two key methods used here are: sessionStorage.getItem(key); sessionStorage.setItem(key,stringVal); Note that the value given to setItem and return by getItem has to be a string. If you pass another type you get an error. Don't let that limit you though - you can easily enough store JSON data in a variable so it's quite possible to pass complex objects and store them into a single sessionStorage value:var user = { name: "Rick", id="ricks", level=8 } sessionStorage.setItem("app_user",JSON.stringify(user)); to retrieve it:var user = sessionStorage.getItem("app_user"); if (user) user = JSON.parse(user); Simple! If you're using the Chrome Developer Tools (F12) you can also check out the session and local storage state on the Resource tab:   You can also use this tool to refresh or remove entries from storage. What we just looked at is a purely client side implementation where a couple of counters are stored. For rich client centric AJAX applications sessionStorage and localStorage provide a very nice and simple API to store application state while the application is running. But you can also use these storage mechanisms to manage server centric HTML applications when you combine server rendering with some JavaScript to perform client side data caching. You can both store some state information and data on the client (ie. store a JSON object and carry it forth between server rendered HTML requests) or you can use it for good old HTTP based caching where some rendered HTML is saved and then restored later. Let's look at the latter with a real life example. Why do I need Client-side Page Caching for Server Rendered HTML? I don't know about you, but in a lot of my existing server driven applications I have lists that display a fair amount of data. Typically these lists contain links to then drill down into more specific data either for viewing or editing. You can then click on a link and go off to a detail page that provides more concise content. So far so good. But now you're done with the detail page and need to get back to the list, so you click on a 'bread crumbs trail' or an application level 'back to list' button and… …you end up back at the top of the list - the scroll position, the current selection in some cases even filters conditions - all gone with the wind. You've left behind the state of the list and are starting from scratch in your browsing of the list from the top. Not cool! Sound familiar? This a pretty common scenario with server rendered HTML content where it's so common to display lists to drill into, only to lose state in the process of returning back to the original list. Look at just about any traditional forums application, or even StackOverFlow to see what I mean here. Scroll down a bit to look at a post or entry, drill in then use the bread crumbs or tab to go back… In some cases returning to the top of a list is not a big deal. On StackOverFlow that sort of works because content is turning around so quickly you probably want to actually look at the top posts. Not always though - if you're browsing through a list of search topics you're interested in and drill in there's no way back to that position. Essentially anytime you're actively browsing the items in the list, that's when state becomes important and if it's not handled the user experience can be really disrupting. Content Caching If you're building client centric SPA style applications this is a fairly easy to solve problem - you tend to render the list once and then update the page content to overlay the detail content, only hiding the list temporarily until it's used again later. It's relatively easy to accomplish this simply by hiding content on the page and later making it visible again. But if you use server rendered content, hanging on to all the detail like filters, selections and scroll position is not quite as easy. Or is it??? This is where sessionStorage comes in handy. What if we just save the rendered content of a previous page, and then restore it when we return to this page based on a special flag that tells us to use the cached version? Let's see how we can do this. A real World Use Case Recently my local ISP asked me to help out with updating an ancient classifieds application. They had a very busy, local classifieds app that was originally an ASP classic application. The old app was - wait for it: frames based - and even though I lobbied against it, the decision was made to keep the frames based layout to allow rapid browsing of the hundreds of posts that are made on a daily basis. The primary reason they wanted this was precisely for the ability to quickly browse content item by item. While I personally hate working with Frames, I have to admit that the UI actually works well with the frames layout as long as you're running on a large desktop screen. You can check out the frames based desktop site here: http://classifieds.gorge.net/ However when I rebuilt the app I also added a secondary view that doesn't use frames. The main reason for this of course was for mobile displays which work horribly with frames. So there's a somewhat mobile friendly interface to the interface, which ditches the frames and uses some responsive design tweaking for mobile capable operation: http://classifeds.gorge.net/mobile  (or browse the base url with your browser width under 800px)   Here's what the mobile, non-frames view looks like:   As you can see this means that the list of classifieds posts now is a list and there's a separate page for drilling down into the item. And of course… originally we ran into that usability issue I mentioned earlier where the browse, view detail, go back to the list cycle resulted in lost list state. Originally in mobile mode you scrolled through the list, found an item to look at and drilled in to display the item detail. Then you clicked back to the list and BAM - you've lost your place. Because there are so many items added on a daily basis the full list is never fully loaded, but rather there's a "Load Additional Listings"  entry at the button. Not only did we originally lose our place when coming back to the list, but any 'additionally loaded' items are no longer there because the list was now rendering  as if it was the first page hit. The additional listings, and any filters, the selection of an item all were lost. Major Suckage! Using Client SessionStorage to cache Server Rendered Content To work around this problem I decided to cache the rendered page content from the list in SessionStorage. Anytime the list renders or is updated with Load Additional Listings, the page HTML is cached and stored in Session Storage. Any back links from the detail page or the login or write entry forms then point back to the list page with a back=true query string parameter. If the server side sees this parameter it doesn't render the part of the page that is cached. Instead the client side code retrieves the data from the sessionState cache and simply inserts it into the page. It sounds pretty simple, and the overall the process is really easy, but there are a few gotchas that I'll discuss in a minute. But first let's look at the implementation. Let's start with the server side here because that'll give a quick idea of the doc structure. As I mentioned the server renders data from an ASP.NET MVC view. On the list page when returning to the list page from the display page (or a host of other pages) looks like this: https://classifieds.gorge.net/list?back=True The query string value is a flag, that indicates whether the server should render the HTML. Here's what the top level MVC Razor view for the list page looks like:@model MessageListViewModel @{ ViewBag.Title = "Classified Listing"; bool isBack = !string.IsNullOrEmpty(Request.QueryString["back"]); } <form method="post" action="@Url.Action("list")"> <div id="SizingContainer"> @if (!isBack) { @Html.Partial("List_CommandBar_Partial", Model) <div id="PostItemContainer" class="scrollbox" xstyle="-webkit-overflow-scrolling: touch;"> @Html.Partial("List_Items_Partial", Model) @if (Model.RequireLoadEntry) { <div class="postitem loadpostitems" style="padding: 15px;"> <div id="LoadProgress" class="smallprogressright"></div> <div class="control-progress"> Load additional listings... </div> </div> } </div> } </div> </form> As you can see the query string triggers a conditional block that if set is simply not rendered. The content inside of #SizingContainer basically holds  the entire page's HTML sans the headers and scripts, but including the filter options and menu at the top. In this case this makes good sense - in other situations the fact that the menu or filter options might be dynamically updated might make you only cache the list rather than essentially the entire page. In this particular instance all of the content works and produces the proper result as both the list along with any filter conditions in the form inputs are restored. Ok, let's move on to the client. On the client there are two page level functions that deal with saving and restoring state. Like the counter example I showed earlier, I like to wrap the logic to save and restore values from sessionState into a separate function because they are almost always used in several places.page.saveData = function(id) { if (!sessionStorage) return; var data = { id: id, scroll: $("#PostItemContainer").scrollTop(), html: $("#SizingContainer").html() }; sessionStorage.setItem("list_html",JSON.stringify(data)); }; page.restoreData = function() { if (!sessionStorage) return; var data = sessionStorage.getItem("list_html"); if (!data) return null; return JSON.parse(data); }; The data that is saved is an object which contains an ID which is the selected element when the user clicks and a scroll position. These two values are used to reset the scroll position when the data is used from the cache. Finally the html from the #SizingContainer element is stored, which makes for the bulk of the document's HTML. In this application the HTML captured could be a substantial bit of data. If you recall, I mentioned that the server side code renders a small chunk of data initially and then gets more data if the user reads through the first 50 or so items. The rest of the items retrieved can be rather sizable. Other than the JSON deserialization that's Ok. Since I'm using SessionStorage the storage space has no immediate limits. Next is the core logic to handle saving and restoring the page state. At first though this would seem pretty simple, and in some cases it might be, but as the following code demonstrates there are a few gotchas to watch out for. Here's the relevant code I use to save and restore:$( function() { … var isBack = getUrlEncodedKey("back", location.href); if (isBack) { // remove the back key from URL setUrlEncodedKey("back", "", location.href); var data = page.restoreData(); // restore from sessionState if (!data) { // no data - force redisplay of the server side default list window.location = "list"; return; } $("#SizingContainer").html(data.html); var el = $(".postitem[data-id=" + data.id + "]"); $(".postitem").removeClass("highlight"); el.addClass("highlight"); $("#PostItemContainer").scrollTop(data.scroll); setTimeout(function() { el.removeClass("highlight"); }, 2500); } else if (window.noFrames) page.saveData(null); // save when page loads $("#SizingContainer").on("click", ".postitem", function() { var id = $(this).attr("data-id"); if (!id) return true; if (window.noFrames) page.saveData(id); var contentFrame = window.parent.frames["Content"]; if (contentFrame) contentFrame.location.href = "show/" + id; else window.location.href = "show/" + id; return false; }); … The code starts out by checking for the back query string flag which triggers restoring from the client cache. If cached the cached data structure is read from sessionStorage. It's important here to check if data was returned. If the user had back=true on the querystring but there is no cached data, he likely bookmarked this page or otherwise shut down the browser and came back to this URL. In that case the server didn't render any detail and we have no cached data, so all we can do is redirect to the original default list view using window.location. If we continued the page would render no data - so make sure to always check the cache retrieval result. Always! If there is data the it's loaded and the data.html data is restored back into the document by simply injecting the HTML back into the document's #SizingContainer element:$("#SizingContainer").html(data.html); It's that simple and it's quite quick even with a fully loaded list of additional items and on a phone. The actual HTML data is stored to the cache on every page load initially and then again when the user clicks on an element to navigate to a particular listing. The former ensures that the client cache always has something in it, and the latter updates with additional information for the selected element. For the click handling I use a data-id attribute on the list item (.postitem) in the list and retrieve the id from that. That id is then used to navigate to the actual entry as well as storing that Id value in the saved cached data. The id is used to reset the selection by searching for the data-id value in the restored elements. The overall process of this save/restore process is pretty straight forward and it doesn't require a bunch of code, yet it yields a huge improvement in the usability of the site on mobile devices (or anybody who uses the non-frames view). Some things to watch out for As easy as it conceptually seems to simply store and retrieve cached content, you have to be quite aware what type of content you are caching. The code above is all that's specific to cache/restore cycle and it works, but it took a few tweaks to the rest of the script code and server code to make it all work. There were a few gotchas that weren't immediately obvious. Here are a few things to pay attention to: Event Handling Logic Timing of manipulating DOM events Inline Script Code Bookmarking to the Cache Url when no cache exists Do you have inline script code in your HTML? That script code isn't going to run if you restore from cache and simply assign or it may not run at the time you think it would normally in the DOM rendering cycle. JavaScript Event Hookups The biggest issue I ran into with this approach almost immediately is that originally I had various static event handlers hooked up to various UI elements that are now cached. If you have an event handler like:$("#btnSearch").click( function() {…}); that works fine when the page loads with server rendered HTML, but that code breaks when you now load the HTML from cache. Why? Because the elements you're trying to hook those events to may not actually be there - yet. Luckily there's an easy workaround for this by using deferred events. With jQuery you can use the .on() event handler instead:$("#SelectionContainer").on("click","#btnSearch", function() {…}); which monitors a parent element for the events and checks for the inner selector elements to handle events on. This effectively defers to runtime event binding, so as more items are added to the document bindings still work. For any cached content use deferred events. Timing of manipulating DOM Elements Along the same lines make sure that your DOM manipulation code follows the code that loads the cached content into the page so that you don't manipulate DOM elements that don't exist just yet. Ideally you'll want to check for the condition to restore cached content towards the top of your script code, but that can be tricky if you have components or other logic that might not all run in a straight line. Inline Script Code Here's another small problem I ran into: I use a DateTime Picker widget I built a while back that relies on the jQuery date time picker. I also created a helper function that allows keyboard date navigation into it that uses JavaScript logic. Because MVC's limited 'object model' the only way to embed widget content into the page is through inline script. This code broken when I inserted the cached HTML into the page because the script code was not available when the component actually got injected into the page. As the last bullet - it's a matter of timing. There's no good work around for this - in my case I pulled out the jQuery date picker and relied on native <input type="date" /> logic instead - a better choice these days anyway, especially since this view is meant to be primarily to serve mobile devices which actually support date input through the browser (unlike desktop browsers of which only WebKit seems to support it). Bookmarking Cached Urls When you cache HTML content you have to make a decision whether you cache on the client and also not render that same content on the server. In the Classifieds app I didn't render server side content so if the user comes to the page with back=True and there is no cached content I have to a have a Plan B. Typically this happens when somebody ends up bookmarking the back URL. The easiest and safest solution for this scenario is to ALWAYS check the cache result to make sure it exists and if not have a safe URL to go back to - in this case to the plain uncached list URL which amounts to effectively redirecting. This seems really obvious in hindsight, but it's easy to overlook and not see a problem until much later, when it's not obvious at all why the page is not rendering anything. Don't use <body> to replace Content Since we're practically replacing all the HTML in the page it may seem tempting to simply replace the HTML content of the <body> tag. Don't. The body tag usually contains key things that should stay in the page and be there when it loads. Specifically script tags and elements and possibly other embedded content. It's best to create a top level DOM element specifically as a placeholder container for your cached content and wrap just around the actual content you want to replace. In the app above the #SizingContainer is that container. Other Approaches The approach I've used for this application is kind of specific to the existing server rendered application we're running and so it's just one approach you can take with caching. However for server rendered content caching this is a pattern I've used in a few apps to retrofit some client caching into list displays. In this application I took the path of least resistance to the existing server rendering logic. Here are a few other ways that come to mind: Using Partial HTML Rendering via AJAXInstead of rendering the page initially on the server, the page would load empty and the client would render the UI by retrieving the respective HTML and embedding it into the page from a Partial View. This effectively makes the initial rendering and the cached rendering logic identical and removes the server having to decide whether this request needs to be rendered or not (ie. not checking for a back=true switch). All the logic related to caching is made on the client in this case. Using JSON Data and Client RenderingThe hardcore client option is to do the whole UI SPA style and pull data from the server and then use client rendering or databinding to pull the data down and render using templates or client side databinding with knockout/angular et al. As with the Partial Rendering approach the advantage is that there's no difference in the logic between pulling the data from cache or rendering from scratch other than the initial check for the cache request. Of course if the app is a  full on SPA app, then caching may not be required even - the list could just stay in memory and be hidden and reactivated. I'm sure there are a number of other ways this can be handled as well especially using  AJAX. AJAX rendering might simplify the logic, but it also complicates search engine optimization since there's no content loaded initially. So there are always tradeoffs and it's important to look at all angles before deciding on any sort of caching solution in general. State of the Session SessionState and LocalStorage are easy to use in client code and can be integrated even with server centric applications to provide nice caching features of content and data. In this post I've shown a very specific scenario of storing HTML content for the purpose of remembering list view data and state and making the browsing experience for lists a bit more friendly, especially if there's dynamically loaded content involved. If you haven't played with sessionStorage or localStorage I encourage you to give it a try. There's a lot of cool stuff that you can do with this beyond the specific scenario I've covered here… Resources Overview of localStorage (also applies to sessionStorage) Web Storage Compatibility Modernizr Test Suite© Rick Strahl, West Wind Technologies, 2005-2013Posted in JavaScript  HTML5  ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Call Webservices&hellip;Maybe!?

  - by MOSSLover

  So I have been doing preliminary work for my iOS talk for a while, but did not get into the meat of the project until recently.  One day I envision my talk uploading pictures from a camera on an iPhone or iPad into SharePoint and telling people how I did it.  As you know with my Silverlight talk and any new technology, building new talks with new technologies always ends up with some pain points that you must jump over just to grab data.  So step 1 always starts out with how do we even access a webservice using the new technology. I started out watching every single SPC video available on oAuth and Rest Webservices in SharePoint 2013.  I also sent an email to Eric Shupps about some REST and 2013 examples.  The videos further confused me, because all the videos were on SharePoint hosted apps (provider and autohosted).  I did not want to create a SharePoint hosted app, but instead a mobile app outside of the SharePoint context altogether.  Nick Swan sent me his code and it was great for a starting point on how the JSON calls would look like on iOS, but I was still missing a piece.  Nick does a great job on showing how to use the REST/JSON calls in a non-MS tech, however his presentation uses the SharePoint context and can grab the SPAppToken.  At this point I had to ask the question how do you grab the SAML token outside of SharePoint 2013 in iOS using Objective-C?  After reading all the MSDN documentation, some documentation on Restkit and Objective-C/oAuth calls, and some SharePoint 2013 blog post my head was swimming.  I was dreaming about REST and iOS in SharePoint 2013.  SAML tokens were taunting me.  I was nowhere near understanding 2013. I started talking to my friend, Pedro Jimenez, who is also playing with Objective-C and went to SPC.  He found me a couple good MSDN posts with REST/JSON calls that basically showed the accessToken was all I needed (at this point I was still thinking iOS needed to be a provider hosted app which is wrong).  So then again I had to ask the SAML token question…How do you get a SAML token outside of SharePoint without the TokenHelper class? So then I started talking to people and thinking why do I need to completely avoid TokenHelper…The solution in concept is basically create a webservice in Azure wrapped into a Provider Hosted App in SharePoint.  Wictor Wilen created a helper webservice in the following blog post: http://www.wictorwilen.se/Post/How-to-do-active-authentication-to-Office-365-and-SharePoint-Online.aspx. So now I have to basically stand up the webservice, the SharePoint app wrapper, and then use Restkit to call the first webservice to grab the token and then the second webservice to pass in the token and grab some SharePoint data.  What this means is that you can no longer just pass credentials into SharePoint webservices and get data back.  You have to pass in a SAML token with every single webservice call to SharePoint.  The theory is that this token is associated with the permissions the app can handle (read, write, whatever).  It seems like a ton of pain and a lot of work, but this is step 1 in my crusade to pull some piece of data into iOS from SharePoint and show people how to do it themselves.  In the upcoming months hopefully I can get halfway to my end goal. Technorati Tags: SharePoint 2013,REST,oAuth,Objective-C,iOS

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• Understanding MotionEvent to implement a virtual DPad and Buttons on Android (Multitouch)

  - by Fabio Gomes

  I once implemented a DPad in XNA and now I'm trying to port it to android, put, I still don't get how the touch events work in android, the more I read the more confused I get. Here is the code I wrote so far, it works, but guess that it will only handle one touch point. public boolean onTouchEvent(MotionEvent event) { if (event.getPointerCount() == 0) return true; int touchX = -1; int touchY = -1; pressedDirection = DPadDirection.None; int actionCode = event.getAction() & MotionEvent.ACTION_MASK; if (actionCode == MotionEvent.ACTION_UP) { if (event.getPointerId(0) == idDPad) { pressedDirection = DPadDirection.None; idDPad = -1; } } else if (actionCode == MotionEvent.ACTION_DOWN || actionCode == MotionEvent.ACTION_MOVE) { touchX = (int)event.getX(); touchY = (int)event.getY(); if (rightRect.contains(touchX, touchY)) pressedDirection = DPadDirection.Right; else if (leftRect.contains(touchX, touchY)) pressedDirection = DPadDirection.Left; else if (upRect.contains(touchX, touchY)) pressedDirection = DPadDirection.Up; else if (downRect.contains(touchX, touchY)) pressedDirection = DPadDirection.Down; if (pressedDirection != DPadDirection.None) idDPad = event.getPointerId(0); } return true; } The logic is: Test if there is a "DOWN" or "MOVED" event, then if one of this events collides with one of the 4 rectangles of my DPad, I set the pressedDirectin variable to the side of the touch event, then I read the DPad actual pressed direction in my Update() event on another class. The thing I'm not sure, is how do I get track of the touch points, I store the ID of the touch point which generated the diretion that is being stored (last one), so when this ID is released I set the Direction to None, but I'm really confused about how to handle this in android, here is the code I had in XNA: public override void Update(GameTime gameTime) { PressedDirection = DpadDirection.None; foreach (TouchLocation _touchLocation in TouchPanel.GetState()) { if (_touchLocation.State == TouchLocationState.Released) { if (_touchLocation.Id == _idDPad) { PressedDirection = DpadDirection.None; _idDPad = -1; } } else if (_touchLocation.State == TouchLocationState.Pressed || _touchLocation.State == TouchLocationState.Moved) { _intersectRect.X = (int)_touchLocation.Position.X; _intersectRect.Y = (int)_touchLocation.Position.Y; _intersectRect.Width = 1; _intersectRect.Height = 1; if (_intersectRect.Intersects(_rightRect)) PressedDirection = DpadDirection.Right; else if (_intersectRect.Intersects(_leftRect)) PressedDirection = DpadDirection.Left; else if (_intersectRect.Intersects(_upRect)) PressedDirection = DpadDirection.Up; else if (_intersectRect.Intersects(_downRect)) PressedDirection = DpadDirection.Down; if (PressedDirection != DpadDirection.None) { _idDPad = _touchLocation.Id; continue; } } } base.Update(gameTime); } So, first of all: Am I doing this correctly? if not, why? I don't want my DPad to handle multiple directions, but I still didn't get how to handle the multiple touch points, is the event called for every touch point, or all touch points comes in a single call? I still don't get it.

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• Using the ASP.NET Membership API with SQL Server / SQL Azure: The new &ldquo;System.Web.Providers&rdquo; namespace

  - by Harish Ranganathan

  The Membership API came in .NET 2.0 and was a huge enhancement in building web applications with users, managing roles, permissions etc.,  The Membership API by default uses SQL Express and until Visual Studio 2008, it was available only through the ASP.NET Configuration manager screen (Website – ASP.NET Configuration) or (Project – ASP.NET Configuration) and for every application, one has to manually visit this place to start using the Security and other settings.  Upon doing that the default SQL Express database aspnet.mdf is created to store all the user profiles. Starting Visual Studio 2010 and .NET 4.0, the Default Website template includes the Membership API controls as a part of the page i.e. When you create a “File – New – ASP.NET Web Application” or an “ASP.NET MVC Application”, by default the Login/Register controls are enabled in the MasterPage and they are termed under “ApplicationServices” setting in the web.config file with connection string pointed to the SQL Express database. In fact, when you run the default website and click on “Logon” –> “Register”, and enter the details for registration and click “Register”, that is the time the aspnet.mdf file is created with the tables for Users, Roles, UsersInRoles, Profile etc., Now, this uses the default SQL Express database within the App_Data folder.  If you want to move your Membership information to some other database such as SQL Server, SQL CE or SQL Azure, you need to manually run the aspnet_regsql command and specify the destination database name. This would create all the Tables, Procedures and Views required to handle the Membership information.  Thereafter you can change the connection string for “ApplicationServices” to point to the database where you had run all the scripts. Now, enter “System.Web.Providers” Alpha. This is available as a part of the NuGet package library.  Scott Hanselman has a neat post describing the steps required to get it up and running as well as doing the basic changes  at http://www.hanselman.com/blog/IntroducingSystemWebProvidersASPNETUniversalProvidersForSessionMembershipRolesAndUserProfileOnSQLCompactAndSQLAzure.aspx Pretty much, it covers what the new System.Web.Providers do. One thing I wanted to clarify is that, the new “System.Web.Providers” add a lot of new settings which are also marked as the defaults, in the web.config.  Even now, they use SQL Express as the default database.  But, if you change the connection string for “DefaultConnection” under connectionStrings to point to your SQL Server or SQL Azure, Membership API would now be able to create all the tables, procedures and views at the destination specified (i.e. SQL Server or SQL Azure). In my case, I modified the DefaultConneciton to point to my SQL Azure database.  Next, I hit F5 to run the application.  The default view loads.  I clicked on “LogOn” and then “Register” since I knew there are no tables/users as of then.  One thing to note is that, I had put “NewDB” as the database name in the connection string that points to SQL Azure.  NewDB wasn’t existing and I would assume it would be created before the tables/views/procedures for Membership are created. Once I clicked on the “Register” to register my first username, it took a while and then registered as well as logged in me in.  Also, I went to the SQL Azure Management Portal and verified that there exists “NewDB” which has just been created I could also connect to the SQL Azure database “NewDB” from Management Studio and found that the tables now don’t have the aspnet_ prefix.  The tables were simply Users, Roles, UsersInRoles, Profiles etc., So, with a few clicks and configuration change, I could actually set up the user base for my application on SQL Azure and even make the SessionState, Roles, Profiles being stored in SQL Azure database. The new System.Web.Proivders also required MARS (MultipleActiveResultSets=true) setting since it uses Entity Framework for the DAL operations.  Also, the “Project – ASP.NET Configuration” screen can be used to further create/manage users/roles etc., although the data is stored on the remote database. With that, a long pending request from the community to have the ability to configure and use remote databases for Application users management without having to run the scripts from SQL Express is fulfilled. Cheers !!!

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• Metro: Creating an IndexedDbDataSource for WinJS

  - by Stephen.Walther

  The goal of this blog entry is to describe how you can create custom data sources which you can use with the controls in the WinJS library. In particular, I explain how you can create an IndexedDbDataSource which you can use to store and retrieve data from an IndexedDB database. If you want to skip ahead, and ignore all of the fascinating content in-between, I’ve included the complete code for the IndexedDbDataSource at the very bottom of this blog entry. What is IndexedDB? IndexedDB is a database in the browser. You can use the IndexedDB API with all modern browsers including Firefox, Chrome, and Internet Explorer 10. And, of course, you can use IndexedDB with Metro style apps written with JavaScript. If you need to persist data in a Metro style app written with JavaScript then IndexedDB is a good option. Each Metro app can only interact with its own IndexedDB databases. And, IndexedDB provides you with transactions, indices, and cursors – the elements of any modern database. An IndexedDB database might be different than the type of database that you normally use. An IndexedDB database is an object-oriented database and not a relational database. Instead of storing data in tables, you store data in object stores. You store JavaScript objects in an IndexedDB object store. You create new IndexedDB object stores by handling the upgradeneeded event when you attempt to open a connection to an IndexedDB database. For example, here’s how you would both open a connection to an existing database named TasksDB and create the TasksDB database when it does not already exist: var reqOpen = window.indexedDB.open(“TasksDB”, 2); reqOpen.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement: true }); }; reqOpen.onsuccess = function () { var db = reqOpen.result; // Do something with db }; When you call window.indexedDB.open(), and the database does not already exist, then the upgradeneeded event is raised. In the code above, the upgradeneeded handler creates a new object store named tasks. The new object store has an auto-increment column named id which acts as the primary key column. If the database already exists with the right version, and you call window.indexedDB.open(), then the success event is raised. At that point, you have an open connection to the existing database and you can start doing something with the database. You use asynchronous methods to interact with an IndexedDB database. For example, the following code illustrates how you would add a new object to the tasks object store: var transaction = db.transaction(“tasks”, “readwrite”); var reqAdd = transaction.objectStore(“tasks”).add({ name: “Feed the dog” }); reqAdd.onsuccess = function() { // Tasks added successfully }; The code above creates a new database transaction, adds a new task to the tasks object store, and handles the success event. If the new task gets added successfully then the success event is raised. Creating a WinJS IndexedDbDataSource The most powerful control in the WinJS library is the ListView control. This is the control that you use to display a collection of items. If you want to display data with a ListView control, you need to bind the control to a data source. The WinJS library includes two objects which you can use as a data source: the List object and the StorageDataSource object. The List object enables you to represent a JavaScript array as a data source and the StorageDataSource enables you to represent the file system as a data source. If you want to bind an IndexedDB database to a ListView then you have a choice. You can either dump the items from the IndexedDB database into a List object or you can create a custom data source. I explored the first approach in a previous blog entry. In this blog entry, I explain how you can create a custom IndexedDB data source. Implementing the IListDataSource Interface You create a custom data source by implementing the IListDataSource interface. This interface contains the contract for the methods which the ListView needs to interact with a data source. The easiest way to implement the IListDataSource interface is to derive a new object from the base VirtualizedDataSource object. The VirtualizedDataSource object requires a data adapter which implements the IListDataAdapter interface. Yes, because of the number of objects involved, this is a little confusing. Your code ends up looking something like this: var IndexedDbDataSource = WinJS.Class.derive( WinJS.UI.VirtualizedDataSource, function (dbName, dbVersion, objectStoreName, upgrade, error) { this._adapter = new IndexedDbDataAdapter(dbName, dbVersion, objectStoreName, upgrade, error); this._baseDataSourceConstructor(this._adapter); }, { nuke: function () { this._adapter.nuke(); }, remove: function (key) { this._adapter.removeInternal(key); } } ); The code above is used to create a new class named IndexedDbDataSource which derives from the base VirtualizedDataSource class. In the constructor for the new class, the base class _baseDataSourceConstructor() method is called. A data adapter is passed to the _baseDataSourceConstructor() method. The code above creates a new method exposed by the IndexedDbDataSource named nuke(). The nuke() method deletes all of the objects from an object store. The code above also overrides a method named remove(). Our derived remove() method accepts any type of key and removes the matching item from the object store. Almost all of the work of creating a custom data source goes into building the data adapter class. The data adapter class implements the IListDataAdapter interface which contains the following methods: · change() · getCount() · insertAfter() · insertAtEnd() · insertAtStart() · insertBefore() · itemsFromDescription() · itemsFromEnd() · itemsFromIndex() · itemsFromKey() · itemsFromStart() · itemSignature() · moveAfter() · moveBefore() · moveToEnd() · moveToStart() · remove() · setNotificationHandler() · compareByIdentity Fortunately, you are not required to implement all of these methods. You only need to implement the methods that you actually need. In the case of the IndexedDbDataSource, I implemented the getCount(), itemsFromIndex(), insertAtEnd(), and remove() methods. If you are creating a read-only data source then you really only need to implement the getCount() and itemsFromIndex() methods. Implementing the getCount() Method The getCount() method returns the total number of items from the data source. So, if you are storing 10,000 items in an object store then this method would return the value 10,000. Here’s how I implemented the getCount() method: getCount: function () { var that = this; return new WinJS.Promise(function (complete, error) { that._getObjectStore().then(function (store) { var reqCount = store.count(); reqCount.onerror = that._error; reqCount.onsuccess = function (evt) { complete(evt.target.result); }; }); }); } The first thing that you should notice is that the getCount() method returns a WinJS promise. This is a requirement. The getCount() method is asynchronous which is a good thing because all of the IndexedDB methods (at least the methods implemented in current browsers) are also asynchronous. The code above retrieves an object store and then uses the IndexedDB count() method to get a count of the items in the object store. The value is returned from the promise by calling complete(). Implementing the itemsFromIndex method When a ListView displays its items, it calls the itemsFromIndex() method. By default, it calls this method multiple times to get different ranges of items. Three parameters are passed to the itemsFromIndex() method: the requestIndex, countBefore, and countAfter parameters. The requestIndex indicates the index of the item from the database to show. The countBefore and countAfter parameters represent hints. These are integer values which represent the number of items before and after the requestIndex to retrieve. Again, these are only hints and you can return as many items before and after the request index as you please. Here’s how I implemented the itemsFromIndex method: itemsFromIndex: function (requestIndex, countBefore, countAfter) { var that = this; return new WinJS.Promise(function (complete, error) { that.getCount().then(function (count) { if (requestIndex >= count) { return WinJS.Promise.wrapError(new WinJS.ErrorFromName(WinJS.UI.FetchError.doesNotExist)); } var startIndex = Math.max(0, requestIndex - countBefore); var endIndex = Math.min(count, requestIndex + countAfter + 1); that._getObjectStore().then(function (store) { var index = 0; var items = []; var req = store.openCursor(); req.onerror = that._error; req.onsuccess = function (evt) { var cursor = evt.target.result; if (index < startIndex) { index = startIndex; cursor.advance(startIndex); return; } if (cursor && index < endIndex) { index++; items.push({ key: cursor.value[store.keyPath].toString(), data: cursor.value }); cursor.continue(); return; } results = { items: items, offset: requestIndex - startIndex, totalCount: count }; complete(results); }; }); }); }); } In the code above, a cursor is used to iterate through the objects in an object store. You fetch the next item in the cursor by calling either the cursor.continue() or cursor.advance() method. The continue() method moves forward by one object and the advance() method moves forward a specified number of objects. Each time you call continue() or advance(), the success event is raised again. If the cursor is null then you know that you have reached the end of the cursor and you can return the results. Some things to be careful about here. First, the return value from the itemsFromIndex() method must implement the IFetchResult interface. In particular, you must return an object which has an items, offset, and totalCount property. Second, each item in the items array must implement the IListItem interface. Each item should have a key and a data property. Implementing the insertAtEnd() Method When creating the IndexedDbDataSource, I wanted to go beyond creating a simple read-only data source and support inserting and deleting objects. If you want to support adding new items with your data source then you need to implement the insertAtEnd() method. Here’s how I implemented the insertAtEnd() method for the IndexedDbDataSource: insertAtEnd:function(unused, data) { var that = this; return new WinJS.Promise(function (complete, error) { that._getObjectStore("readwrite").done(function(store) { var reqAdd = store.add(data); reqAdd.onerror = that._error; reqAdd.onsuccess = function (evt) { var reqGet = store.get(evt.target.result); reqGet.onerror = that._error; reqGet.onsuccess = function (evt) { var newItem = { key:evt.target.result[store.keyPath].toString(), data:evt.target.result } complete(newItem); }; }; }); }); } When implementing the insertAtEnd() method, you need to be careful to return an object which implements the IItem interface. In particular, you should return an object that has a key and a data property. The key must be a string and it uniquely represents the new item added to the data source. The value of the data property represents the new item itself. Implementing the remove() Method Finally, you use the remove() method to remove an item from the data source. You call the remove() method with the key of the item which you want to remove. Implementing the remove() method in the case of the IndexedDbDataSource was a little tricky. The problem is that an IndexedDB object store uses an integer key and the VirtualizedDataSource requires a string key. For that reason, I needed to override the remove() method in the derived IndexedDbDataSource class like this: var IndexedDbDataSource = WinJS.Class.derive( WinJS.UI.VirtualizedDataSource, function (dbName, dbVersion, objectStoreName, upgrade, error) { this._adapter = new IndexedDbDataAdapter(dbName, dbVersion, objectStoreName, upgrade, error); this._baseDataSourceConstructor(this._adapter); }, { nuke: function () { this._adapter.nuke(); }, remove: function (key) { this._adapter.removeInternal(key); } } ); When you call remove(), you end up calling a method of the IndexedDbDataAdapter named removeInternal() . Here’s what the removeInternal() method looks like: setNotificationHandler: function (notificationHandler) { this._notificationHandler = notificationHandler; }, removeInternal: function(key) { var that = this; return new WinJS.Promise(function (complete, error) { that._getObjectStore("readwrite").done(function (store) { var reqDelete = store.delete (key); reqDelete.onerror = that._error; reqDelete.onsuccess = function (evt) { that._notificationHandler.removed(key.toString()); complete(); }; }); }); } The removeInternal() method calls the IndexedDB delete() method to delete an item from the object store. If the item is deleted successfully then the _notificationHandler.remove() method is called. Because we are not implementing the standard IListDataAdapter remove() method, we need to notify the data source (and the ListView control bound to the data source) that an item has been removed. The way that you notify the data source is by calling the _notificationHandler.remove() method. Notice that we get the _notificationHandler in the code above by implementing another method in the IListDataAdapter interface: the setNotificationHandler() method. You can raise the following types of notifications using the _notificationHandler: · beginNotifications() · changed() · endNotifications() · inserted() · invalidateAll() · moved() · removed() · reload() These methods are all part of the IListDataNotificationHandler interface in the WinJS library. Implementing the nuke() Method I wanted to implement a method which would remove all of the items from an object store. Therefore, I created a method named nuke() which calls the IndexedDB clear() method: nuke: function () { var that = this; return new WinJS.Promise(function (complete, error) { that._getObjectStore("readwrite").done(function (store) { var reqClear = store.clear(); reqClear.onerror = that._error; reqClear.onsuccess = function (evt) { that._notificationHandler.reload(); complete(); }; }); }); } Notice that the nuke() method calls the _notificationHandler.reload() method to notify the ListView to reload all of the items from its data source. Because we are implementing a custom method here, we need to use the _notificationHandler to send an update. Using the IndexedDbDataSource To illustrate how you can use the IndexedDbDataSource, I created a simple task list app. You can add new tasks, delete existing tasks, and nuke all of the tasks. You delete an item by selecting an item (swipe or right-click) and clicking the Delete button. Here’s the HTML page which contains the ListView, the form for adding new tasks, and the buttons for deleting and nuking tasks: <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>DataSources</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.1.0.RC/css/ui-dark.css" rel="stylesheet" /> <script src="//Microsoft.WinJS.1.0.RC/js/base.js"></script> <script src="//Microsoft.WinJS.1.0.RC/js/ui.js"></script> <!-- DataSources references --> <link href="indexedDb.css" rel="stylesheet" /> <script type="text/javascript" src="indexedDbDataSource.js"></script> <script src="indexedDb.js"></script> </head> <body> <div id="tmplTask" data-win-control="WinJS.Binding.Template"> <div class="taskItem"> Id: <span data-win-bind="innerText:id"></span> <br /><br /> Name: <span data-win-bind="innerText:name"></span> </div> </div> <div id="lvTasks" data-win-control="WinJS.UI.ListView" data-win-options="{ itemTemplate: select('#tmplTask'), selectionMode: 'single' }"></div> <form id="frmAdd"> <fieldset> <legend>Add Task</legend> <label>New Task</label> <input id="inputTaskName" required /> <button>Add</button> </fieldset> </form> <button id="btnNuke">Nuke</button> <button id="btnDelete">Delete</button> </body> </html> And here is the JavaScript code for the TaskList app: /// <reference path="//Microsoft.WinJS.1.0.RC/js/base.js" /> /// <reference path="//Microsoft.WinJS.1.0.RC/js/ui.js" /> function init() { WinJS.UI.processAll().done(function () { var lvTasks = document.getElementById("lvTasks").winControl; // Bind the ListView to its data source var tasksDataSource = new DataSources.IndexedDbDataSource("TasksDB", 1, "tasks", upgrade); lvTasks.itemDataSource = tasksDataSource; // Wire-up Add, Delete, Nuke buttons document.getElementById("frmAdd").addEventListener("submit", function (evt) { evt.preventDefault(); tasksDataSource.beginEdits(); tasksDataSource.insertAtEnd(null, { name: document.getElementById("inputTaskName").value }).done(function (newItem) { tasksDataSource.endEdits(); document.getElementById("frmAdd").reset(); lvTasks.ensureVisible(newItem.index); }); }); document.getElementById("btnDelete").addEventListener("click", function () { if (lvTasks.selection.count() == 1) { lvTasks.selection.getItems().done(function (items) { tasksDataSource.remove(items[0].data.id); }); } }); document.getElementById("btnNuke").addEventListener("click", function () { tasksDataSource.nuke(); }); // This method is called to initialize the IndexedDb database function upgrade(evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement: true }); } }); } document.addEventListener("DOMContentLoaded", init); The IndexedDbDataSource is created and bound to the ListView control with the following two lines of code: var tasksDataSource = new DataSources.IndexedDbDataSource("TasksDB", 1, "tasks", upgrade); lvTasks.itemDataSource = tasksDataSource; The IndexedDbDataSource is created with four parameters: the name of the database to create, the version of the database to create, the name of the object store to create, and a function which contains code to initialize the new database. The upgrade function creates a new object store named tasks with an auto-increment property named id: function upgrade(evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement: true }); } The Complete Code for the IndexedDbDataSource Here’s the complete code for the IndexedDbDataSource: (function () { /************************************************ * The IndexedDBDataAdapter enables you to work * with a HTML5 IndexedDB database. *************************************************/ var IndexedDbDataAdapter = WinJS.Class.define( function (dbName, dbVersion, objectStoreName, upgrade, error) { this._dbName = dbName; // database name this._dbVersion = dbVersion; // database version this._objectStoreName = objectStoreName; // object store name this._upgrade = upgrade; // database upgrade script this._error = error || function (evt) { console.log(evt.message); }; }, { /******************************************* * IListDataAdapter Interface Methods ********************************************/ getCount: function () { var that = this; return new WinJS.Promise(function (complete, error) { that._getObjectStore().then(function (store) { var reqCount = store.count(); reqCount.onerror = that._error; reqCount.onsuccess = function (evt) { complete(evt.target.result); }; }); }); }, itemsFromIndex: function (requestIndex, countBefore, countAfter) { var that = this; return new WinJS.Promise(function (complete, error) { that.getCount().then(function (count) { if (requestIndex >= count) { return WinJS.Promise.wrapError(new WinJS.ErrorFromName(WinJS.UI.FetchError.doesNotExist)); } var startIndex = Math.max(0, requestIndex - countBefore); var endIndex = Math.min(count, requestIndex + countAfter + 1); that._getObjectStore().then(function (store) { var index = 0; var items = []; var req = store.openCursor(); req.onerror = that._error; req.onsuccess = function (evt) { var cursor = evt.target.result; if (index < startIndex) { index = startIndex; cursor.advance(startIndex); return; } if (cursor && index < endIndex) { index++; items.push({ key: cursor.value[store.keyPath].toString(), data: cursor.value }); cursor.continue(); return; } results = { items: items, offset: requestIndex - startIndex, totalCount: count }; complete(results); }; }); }); }); }, insertAtEnd:function(unused, data) { var that = this; return new WinJS.Promise(function (complete, error) { that._getObjectStore("readwrite").done(function(store) { var reqAdd = store.add(data); reqAdd.onerror = that._error; reqAdd.onsuccess = function (evt) { var reqGet = store.get(evt.target.result); reqGet.onerror = that._error; reqGet.onsuccess = function (evt) { var newItem = { key:evt.target.result[store.keyPath].toString(), data:evt.target.result } complete(newItem); }; }; }); }); }, setNotificationHandler: function (notificationHandler) { this._notificationHandler = notificationHandler; }, /***************************************** * IndexedDbDataSource Method ******************************************/ removeInternal: function(key) { var that = this; return new WinJS.Promise(function (complete, error) { that._getObjectStore("readwrite").done(function (store) { var reqDelete = store.delete (key); reqDelete.onerror = that._error; reqDelete.onsuccess = function (evt) { that._notificationHandler.removed(key.toString()); complete(); }; }); }); }, nuke: function () { var that = this; return new WinJS.Promise(function (complete, error) { that._getObjectStore("readwrite").done(function (store) { var reqClear = store.clear(); reqClear.onerror = that._error; reqClear.onsuccess = function (evt) { that._notificationHandler.reload(); complete(); }; }); }); }, /******************************************* * Private Methods ********************************************/ _ensureDbOpen: function () { var that = this; // Try to get cached Db if (that._cachedDb) { return WinJS.Promise.wrap(that._cachedDb); } // Otherwise, open the database return new WinJS.Promise(function (complete, error, progress) { var reqOpen = window.indexedDB.open(that._dbName, that._dbVersion); reqOpen.onerror = function (evt) { error(); }; reqOpen.onupgradeneeded = function (evt) { that._upgrade(evt); that._notificationHandler.invalidateAll(); }; reqOpen.onsuccess = function () { that._cachedDb = reqOpen.result; complete(that._cachedDb); }; }); }, _getObjectStore: function (type) { type = type || "readonly"; var that = this; return new WinJS.Promise(function (complete, error) { that._ensureDbOpen().then(function (db) { var transaction = db.transaction(that._objectStoreName, type); complete(transaction.objectStore(that._objectStoreName)); }); }); }, _get: function (key) { return new WinJS.Promise(function (complete, error) { that._getObjectStore().done(function (store) { var reqGet = store.get(key); reqGet.onerror = that._error; reqGet.onsuccess = function (item) { complete(item); }; }); }); } } ); var IndexedDbDataSource = WinJS.Class.derive( WinJS.UI.VirtualizedDataSource, function (dbName, dbVersion, objectStoreName, upgrade, error) { this._adapter = new IndexedDbDataAdapter(dbName, dbVersion, objectStoreName, upgrade, error); this._baseDataSourceConstructor(this._adapter); }, { nuke: function () { this._adapter.nuke(); }, remove: function (key) { this._adapter.removeInternal(key); } } ); WinJS.Namespace.define("DataSources", { IndexedDbDataSource: IndexedDbDataSource }); })(); Summary In this blog post, I provided an overview of how you can create a new data source which you can use with the WinJS library. I described how you can create an IndexedDbDataSource which you can use to bind a ListView control to an IndexedDB database. While describing how you can create a custom data source, I explained how you can implement the IListDataAdapter interface. You also learned how to raise notifications — such as a removed or invalidateAll notification — by taking advantage of the methods of the IListDataNotificationHandler interface.

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• Improving performance of a particle system (OpenGL ES)

  - by Jason

  I'm in the process of implementing a simple particle system for a 2D mobile game (using OpenGL ES 2.0). It's working, but it's pretty slow. I start getting frame rate battering after about 400 particles, which I think is pretty low. Here's a summary of my approach: I start with point sprites (GL_POINTS) rendered in a batch just using a native float buffer (I'm in Java-land on Android, so that translates as a java.nio.FloatBuffer). On GL context init, the following are set: GLES20.glViewport(0, 0, width, height); GLES20.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); GLES20.glEnable(GLES20.GL_CULL_FACE); GLES20.glDisable(GLES20.GL_DEPTH_TEST); Each draw frame sets the following: GLES20.glEnable(GLES20.GL_BLEND); GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA); And I bind a single texture: GLES20.glActiveTexture(GLES20.GL_TEXTURE0); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureHandle); GLES20.glUniform1i(mUniformTextureHandle, 0); Which is just a simple circle with some blur (and hence some transparency) http://cl.ly/image/0K2V2p2L1H2x Then there are a bunch of glVertexAttribPointer calls: mBuffer.position(position); mGlEs20.glVertexAttribPointer(mAttributeRGBHandle, valsPerRGB, GLES20.GL_FLOAT, false, stride, mBuffer); ...4 more of these Then I'm drawing: GLES20.glUniformMatrix4fv(mUniformProjectionMatrixHandle, 1, false, Camera.mProjectionMatrix, 0); GLES20.glDrawArrays(GLES20.GL_POINTS, 0, drawCalls); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0); My vertex shader does have some computation in it, but given that they're point sprites (with only 2 coordinate values) I'm not sure this is the problem: #ifdef GL_ES // Set the default precision to low. precision lowp float; #endif uniform mat4 u_ProjectionMatrix; attribute vec4 a_Position; attribute float a_PointSize; attribute vec3 a_RGB; attribute float a_Alpha; attribute float a_Burn; varying vec4 v_Color; void main() { vec3 v_FGC = a_RGB * a_Alpha; v_Color = vec4(v_FGC.x, v_FGC.y, v_FGC.z, a_Alpha * (1.0 - a_Burn)); gl_PointSize = a_PointSize; gl_Position = u_ProjectionMatrix * a_Position; } My fragment shader couldn't really be simpler: #ifdef GL_ES // Set the default precision to low. precision lowp float; #endif uniform sampler2D u_Texture; varying vec4 v_Color; void main() { gl_FragColor = texture2D(u_Texture, gl_PointCoord) * v_Color; } That's about it. I had read that transparent pixels in point sprites can cause issues, but surely not at only 400 points? I'm running on a fairly new device (12 month old Galaxy Nexus). My question is less about my approach (although I'm open to suggestion) but more about whether there are any specific OpenGL "no no's" that have leaked into my code. I'm sure there's GL master out there facepalming right now... I'd love to hear any critique.

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• Configuring Multiple Instances of MySQL in Solaris 11

  - by rajeshr

  Recently someone asked me for steps to configure multiple instances of MySQL database in an Operating Platform. Coz of my familiarity with Solaris OE, I prepared some notes on configuring multiple instances of MySQL database on Solaris 11. Maybe it's useful for some: If you want to run Solaris Operating System (or any other OS of your choice) as a virtualized instance in desktop, consider using Virtual Box. To download Solaris Operating System, click here. Once you have your Solaris Operating System (Version 11) up and running and have Internet connectivity to gain access to the Image Packaging System (IPS), please follow the steps as mentioned below to install MySQL and configure multiple instances: 1. Install MySQL Database in Solaris 11 $ sudo pkg install mysql-51 2. Verify if the mysql is installed: $ svcs -a | grep mysql Note: Service FMRI will look similar to the one here: svc:/application/database/mysql:version_51 3. Prepare data file system for MySQL Instance 1 zfs create rpool/mysql zfs create rpool/mysql/data zfs set mountpoint=/mysql/data rpool/mysql/data 4. Prepare data file system for MySQL Instance 2 zfs create rpool/mysql/data2 zfs set mountpoint=/mysql/data rpool/mysql/data2 5. Change the mysql/datadir of the MySQL Service (SMF) to point to /mysql/data $ svcprop mysql:version_51 | grep mysql/data $ svccfg -s mysql:version_51 setprop mysql/data=/mysql/data 6. Create a new instance of MySQL 5.1 (a) Copy the manifest of the default instance to temporary directory: $ sudo cp /lib/svc/manifest/application/database/mysql_51.xml /var/tmp/mysql_51_2.xml (b) Make appropriate modifications on the XML file $ sudo vi /var/tmp/mysql_51_2.xml - Change the "instance name" section to a new value "version_51_2" - Change the value of property name "data" to point to the ZFS file system "/mysql/data2" 7. Import the manifest to the SMF repository: $ sudo svccfg import /var/tmp/mysql_51_2.xml 8. Before starting the service, copy the file /etc/mysql/my.cnf to the data directories /mysql/data & /mysql/data2. $ sudo cp /etc/mysql/my.cnf /mysql/data/ $ sudo cp /etc/mysql/my.cnf /mysql/data2/ 9. Make modifications to the my.cnf in each of the data directories as required: $ sudo vi /mysql/data/my.cnf Under the [client] section port=3306 socket=/tmp/mysql.sock ---- ---- Under the [mysqld] section port=3306 socket=/tmp/mysql.sock datadir=/mysql/data ----- ----- server-id=1 $ sudo vi /mysql/data2/my.cnf Under the [client] section port=3307 socket=/tmp/mysql2.sock ----- ----- Under the [mysqld] section port=3307 socket=/tmp/mysql2.sock datadir=/mysql/data2 ----- ----- server-id=2 10. Make appropriate modification to the startup script of MySQL (managed by SMF) to point to the appropriate my.cnf for each instance: $ sudo vi /lib/svc/method/mysql_51 Note: Search for all occurences of mysqld_safe command and modify it to include the --defaults-file option. An example entry would look as follows: ${MySQLBIN}/mysqld_safe --defaults-file=${MYSQLDATA}/my.cnf --user=mysql --datadir=${MYSQLDATA} --pid=file=${PIDFILE} 11. Start the service: $ sudo svcadm enable mysql:version_51_2 $ sudo svcadm enable mysql:version_51 12. Verify that the two services are running by using: $ svcs mysql 13. Verify the processes: $ ps -ef | grep mysqld 14. Connect to each mysqld instance and verify: $ mysql --defaults-file=/mysql/data/my.cnf -u root -p $ mysql --defaults-file=/mysql/data2/my.cnf -u root -p Some references for Solaris 11 newbies Taking your first steps with Solaris 11 Introducing the basics of Image Packaging System Service Management Facility How To Guide For a detailed list of official educational modules available on Solaris 11, please visit here For MySQL courses from Oracle University access this page.

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• OS Development. Only Few Particular Questions

  - by Total Anime Immersion

  I am new to this site as a member but have consulted its answers quite a lot of times. Besides my questions regarding OS Development hasn't been answered in any forum. In OS Dev. we make a bootloader. The org point is 7C00H. Why so? Why not 0000h? What are the last two signatures in the bootloader used for? People on every forum have answered that it is important for the system to recognize it as a bootable media. But I want a specific answer. What do each of those signatures do. I have the basic concept of a kernel. Point is.. it relates to different files required in a system. It sort of binds up everything that is individually developed. Now the thing is that that I have floating ideas in my mind regarding different aspects like keyboard, mouse, etc.. how do I put them all together? Which should I start with first? If possible please provide a step by step procedure of the startups of the kernel. Suppose I have developed my language entirely in C and Assembly. Now questions is will exe files work on my system.. if it doesn't then I have to create my own files and publish them. Which is a bad idea.. next step would be for me to go for a compiler for a language which I have designed myself. Now the point is.. How do I implement the compiler into my OS? After all this my final question is that.. How do you go about multitasking and multithreading? and I don't want to use int 21h as its dos specific.. how do I go about making files, renaming them, etc. and all assembly books teach 16 but programming.. how do i go about doing 32 bit or 64 bit with the knowledge I have.. if the basics and instructions are the same.. I don't mind.. but how do i go about otherwise? Don't tell me to give up the idea because I WON'T. And don't tell me it's too complex because I have a sharp knowledge of working of a system, C, Java, Assembly, C++ and python, C#, visual basic.. and not just basics but full fledged api developments.. but I really want to go deep into the systems part.. so I want professional help.. And I have gone through many OS project files but I want help particularly from this site as there are people with knowledge depth who can guide me the right way. And please don't suggest any books above 20$ and they should be available on flipkart as amazon charges massively for shipping and I prefer free shipping from flipkart.

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• When to use Aspect Oriented Architecture (AOA/AOD)

  When is it appropriate to use aspect oriented architecture? I think the only honest answer to this question is that it depends on the context for which the question is being asked. There really are no hard and fast rules regarding the selection of an architectural model(s) for a project because each model provides good and bad benefits. Every system is built with a unique requirements and constraints. This context will dictate when to use one type of architecture over another or in conjunction with others. To me aspect oriented architecture models should be a sub-phase in the architectural modeling and design process especially when creating enterprise level models. Personally, I like to use this approach to create a base architectural model that is defined by non-functional requirements and system quality attributes.   This general model can then be used as a starting point for additional models because it is targets all of the business key quality attributes required by the system.Aspect oriented architecture is a method for modeling non-functional requirements and quality attributes of a system known as aspects. These models do not deal directly with specific functionality. They do categorize functionality of the system. This approach allows a system to be created with a strong emphasis on separating system concerns into individual components. These cross cutting components enables a systems to create with compartmentalization in regards to non-functional requirements or quality attributes.  This allows for the reduction in code because an each component maintains an aspect of a system that can be called by other aspects. This approach also allows for a much cleaner and smaller code base during the implementation and support of a system. Additionally, enabling developers to develop systems based on aspect-oriented design projects will be completed faster and will be more reliable because existing components can be shared across a system; thus, the time needed to create and test the functionality is reduced.   Example of an effective use of Aspect Oriented ArchitectureIn my experiences, aspect oriented architecture can be very effective with large or more complex systems. Typically, these types of systems have a large number of concerns so the act of defining them is very beneficial for reducing the system’s complexity because components can be developed to address each concern while exposing functionality to the other system components. The benefits to using the aspect oriented approach as the starting point for a system is that it promotes communication between IT and the business due to the fact that the aspect oriented models are quality attributes focused so not much technical understanding is needed to understand the model.An example of this can be in developing a new intranet website. Common Intranet Concerns: Error Handling Security Logging Notifications Database connectivity Example of a not as effective use of Aspect Oriented ArchitectureAgain in my experiences, aspect oriented architecture is not as effective with small or less complex systems in comparison.  There is no need to model concerns for a system that has a limited amount of them because the added overhead would not be justified for the actual benefits of creating the aspect oriented architecture model.  Furthermore, these types of projects typically have a reduced time schedule and a limited budget.  The creation of the Aspect oriented models would increase the overhead of a project and thus increase the time needed to implement the system. An example of this is seen by creating a small application to poll a network share for new files and then FTP them to a new location.  The two primary concerns for this project is to monitor a network drive and FTP files to a new location.  There is no need to create an aspect model for this system because there will never be a need to share functionality amongst either of these concerns.  To add to my point, this system is so small that it could be created with just a few classes so the added layer of componentizing the concerns would be complete overkill for this situation. References:Brichau, Johan; D'Hondt, Theo. (2006) Aspect-Oriented Software Development (AOSD) - An Introduction. Retreived from: http://www.info.ucl.ac.be/~jbrichau/courses/introductionToAOSD.pdf

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• First-Time GLSL Shadow Mapping Problems

  - by Locke

  I'm working on building out a 2.5D engine and having massive problems getting my shadows working. I'm at a point where I'm VERY close. So, let's see a picture to see what I have: As you can see above, the image has lighting -- but the shadow map is displaying incorrectly. The shadow map is shown in the bottom left hand side of the screen as a normal 2D texture, so we can see what it looks like at any given time. If you notice, it appears that the shadows are generating backwards in the wrong direction -- I think. But the problem is a little more deep -- I'm just plotting the shadow onto the screen, which I know is wrong -- I'm ignoring the actual test to see if we NEED to show a shadow. The incoming parameters all appear to be correct -- so there has to be something wrong with my shader code somewhere. Here's what my code looks like: VERTEX: uniform mat4 LightModelViewProjectionMatrix; varying vec3 Normal; // The eye-space normal of the current vertex. varying vec4 LightCoordinate; // The texture coordinate of the light of the current vertex. varying vec3 LightDirection; // The eye-space direction of the light. void main() { Normal = normalize(gl_NormalMatrix * gl_Normal); LightDirection = normalize(gl_NormalMatrix * gl_LightSource[0].position.xyz); LightCoordinate = LightModelViewProjectionMatrix * gl_Vertex; LightCoordinate.xy = ( LightCoordinate.xy * 0.5 ) + 0.5; gl_Position = ftransform(); gl_TexCoord[0] = gl_MultiTexCoord0; } FRAGMENT: uniform sampler2D DiffuseMap; uniform sampler2D ShadowMap; varying vec3 Normal; // The eye-space normal of the current vertex. varying vec4 LightCoordinate; // The texture coordinate of the light of the current vertex. varying vec3 LightDirection; // The eye-space direction of the light. void main() { vec4 Texel = texture2D(DiffuseMap, vec2(gl_TexCoord[0])); // Directional lighting //Build ambient lighting vec4 AmbientElement = gl_LightSource[0].ambient; //Build diffuse lighting float Lambert = max(dot(Normal, LightDirection), 0.0); //max(abs(dot(Normal, LightDirection)), 0.0); vec4 DiffuseElement = ( gl_LightSource[0].diffuse * Lambert ); vec4 LightingColor = ( DiffuseElement + AmbientElement ); LightingColor.r = min(LightingColor.r, 1.0); LightingColor.g = min(LightingColor.g, 1.0); LightingColor.b = min(LightingColor.b, 1.0); LightingColor.a = min(LightingColor.a, 1.0); LightingColor *= Texel; //Everything up to this point is PERFECT // Shadow mapping // ------------------------------ vec4 ShadowCoordinate = LightCoordinate / LightCoordinate.w; float DistanceFromLight = texture2D( ShadowMap, ShadowCoordinate.st ).z; float DepthBias = 0.001; float ShadowFactor = 1.0; if( LightCoordinate.w > 0.0 ) { ShadowFactor = DistanceFromLight < ( ShadowCoordinate.z + DepthBias ) ? 0.5 : 1.0; } LightingColor.rgb *= ShadowFactor; //gl_FragColor = LightingColor; //Yes, I know this is wrong, but the line above (gl_FragColor = LightingColor;) produces the wrong effect gl_FragColor = LightingColor * texture2D( ShadowMap, ShadowCoordinate.st ); } I wanted to make sure the coordinates were correct for the shadow map -- so that's why you see it applied to the image as it is below. But the depth for each point seems to be wrong -- the shadows SHOULD be opposite (look at how the image is -- the shaded areas from normal lighting are facing the opposite direction of the shadows). Maybe my matrices are bad or something going in? They're isolated and appear to be correct -- nothing else is going in unusual. When I view from the light's view and get the MVP matrices for it, they're correct. EDIT: Added an image so you can see what happens when I do the correct command at the end of the GLSL: That's the image when the last line is just glFragColor = LightingColor; Maybe someone has some idea of what I screwed up?

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• #altnetseattle &ndash; REST Services

  - by GeekAgilistMercenary

  Below are the notes I made in the REST Architecture Session I helped kick off with Andrew. RSS, ATOM, and such needed for better discovery.  i.e. there still is a need for some type of discovery. Difficult is modeling behaviors in a RESTful way.  ??  Invoking some type of state against an object.  For instance in the case of a POST vs. a GET.  The GET is easy, comes back as is, but what about a POST, which often changes some state or something. Challenge is doing multiple workflows with stateful workflows.  How does batch work.  Maybe model the batch as a resource. Frameworks aren’t particularly part of REST, REST is REST.  But point argued that REST is modeled, or part of modeling a state machine of some sort… ? Nothing is 100% reliable w/ REST – comparisons drawn with TCP/IP.  Sufficient probability is made however for the communications, but the idea of a possible failure has to be built into the usage model of REST. Ruby on Rails / RESTfully, and others used.  What were their issues, what do they do.  ATOM feeds, object serialized, using LINQ to XML w/ this.  No state machine libraries. Idempotent areas around REST and single change POST changes are inherent in the architecture. REST – one of the constrained languages is for the interaction w/ the system.  Limiting what can be done on the resources.  - disagreement, there is no agreed upon REST verbs. Sam Ruby – RESTful services.  Expanded the verbs within REST/HTTP pushes you off the web.  Of the existing verbs POST leaves the most up for debate. Robert Reem used Factory to deal with the POST to handle the new state.  The POST identifying what it just did by the return. Different states are put into POST, so that new prospective verbs, without creating verbs for REST/HTTP can be used to advantage without breaking universal clients. Biggest issue with REST services is their lack of state, yet it is also one of their biggest strengths.  What happens is that the client takes up the often onerous task of handling all state, state machines, and other extraneous resource management.  All the GETs, POSTs, DELETEs, INSERTs get all pushed into abstraction.  My 2 cents is that this in a way ends up pushing a huge proprietary burden onto the REST services often removing the point of REST to be simple and to the point. WADL does provide discovery and some state control (sort of?) Statement made, "WADL" isn't needed.  The JSON, XML, or other client side returned data handles this. I then applied the law of 2 feet rule for myself and headed to finish up these notes, post to the Wiki, and figure out what I was going to do next.  For the original Wiki entry check it out here. I will be adding more to this post with a subsequent post.  Please do feel free to post your thoughts and ideas about this, as I am sure everyone in the session will have more for elaboration.

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• My First Iteration Zero

  - by onefloridacoder

  I recently watched a web cast that covered the idea of planning from the concept stage to the product backlog.  It was the first content I had seen related to Iteration Zero and it made a lot of sense from a planning and engagement perspective where the customer is concerned.  It illuminated some of the problems I’ve experienced with getting a large project of the ground.  The idea behind this is to just figure out get everyone to understand what needs to be constructed and to build the initial feature set from a *very* high level.  Once that happens other parts of the high level construction start to take place.  You end up with a feature list that describes what the business wants the system to do, and what it potentially may (or may not) interact with.  Low tech tools are used to create UI mockups that can be used as a starting point for some of the key UI pieces. Toward the end of the webcast they speaker introduced something that was new to me.  He referred to it as an executable skeleton or the steel thread.  The idea with this part of the webcast was to describe walking through the different mocked layers of the application.  Not all layers and collaborators are involved at this stage since it’s Iteration Zero, and each layer is either hard-coded or completely mocked to provide a 35K foot view of how the different layers layers work together.  So imagine two actors on each side of a layer diagram and the flow goes down from the upper left side down through a a consumer, thorough a service layer and then back up the service layer to the destination/actor. I would imagine much could be discussed moving through new/planned or existing/legacy layers, or a little of both to see what’s implied by the current high-level design. One part of the web cast has the business and design team creating the product box (think of your favorite cereal or toy box) with all of the features and even pictures laid out on the outside of the box.  The notion here is that if you handed this box to someone and told them your system was inside they would have an understanding of what the system would be able to do, or the features it could provide.    One of the interesting parts of the webcast was where the speaker described that he worked with a couple of groups in the same room and each group came up with a different product box – the point is that each group had a different idea of what the system was supposed to do.  At this point of the project I thought that to be valuable considering my experience has been that historically this has taken longer than a week to realize that the business unit and design teams see the high level solution differently.  Once my box is finished I plan on moving to the next stage of solution definition which is to plan the UI for this small application using Excel, to map out the UI elements.  I’m my own customer so it feels like cheating, but taking these slow deliberate steps have already provided a few learning opportunities.    So I resist the urge to load all of my user stories into my newly installed VS2010  TFS project and try to reduce or add to, the number of user stories and/or refine the high level estimates I’ve come up with so far.

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• Determining explosion radius damage - Circle to Rectangle 2D

  - by Paul Renton

  One of the Cocos2D games I am working on has circular explosion effects. These explosion effects need to deal a percentage of their set maximum damage to all game characters (represented by rectangular bounding boxes as the objects in question are tanks) within the explosion radius. So this boils down to circle to rectangle collision and how far away the circle's radius is from the closest rectangle edge. I took a stab at figuring this out last night, but I believe there may be a better way. In particular, I don't know the best way to determine what percentage of damage to apply based on the distance calculated. Note : All tank objects have an anchor point of (0,0) so position is according to bottom left corner of bounding box. Explosion point is the center point of the circular explosion. TankObject * tank = (TankObject*) gameSprite; float distanceFromExplosionCenter; // IMPORTANT :: All GameCharacter have an assumed (0,0) anchor if (explosionPoint.x < tank.position.x) { // Explosion to WEST of tank if (explosionPoint.y <= tank.position.y) { //Explosion SOUTHWEST distanceFromExplosionCenter = ccpDistance(explosionPoint, tank.position); } else if (explosionPoint.y >= (tank.position.y + tank.contentSize.height)) { // Explosion NORTHWEST distanceFromExplosionCenter = ccpDistance(explosionPoint, ccp(tank.position.x, tank.position.y + tank.contentSize.height)); } else { // Exp center's y is between bottom and top corner of rect distanceFromExplosionCenter = tank.position.x - explosionPoint.x; } // end if } else if (explosionPoint.x > (tank.position.x + tank.contentSize.width)) { // Explosion to EAST of tank if (explosionPoint.y <= tank.position.y) { //Explosion SOUTHEAST distanceFromExplosionCenter = ccpDistance(explosionPoint, ccp(tank.position.x + tank.contentSize.width, tank.position.y)); } else if (explosionPoint.y >= (tank.position.y + tank.contentSize.height)) { // Explosion NORTHEAST distanceFromExplosionCenter = ccpDistance(explosionPoint, ccp(tank.position.x + tank.contentSize.width, tank.position.y + tank.contentSize.height)); } else { // Exp center's y is between bottom and top corner of rect distanceFromExplosionCenter = explosionPoint.x - (tank.position.x + tank.contentSize.width); } // end if } else { // Tank is either north or south and is inbetween left and right corner of rect if (explosionPoint.y < tank.position.y) { // Explosion is South distanceFromExplosionCenter = tank.position.y - explosionPoint.y; } else { // Explosion is North distanceFromExplosionCenter = explosionPoint.y - (tank.position.y + tank.contentSize.height); } // end if } // end outer if if (distanceFromExplosionCenter < explosionRadius) { /* Collision :: Smaller distance larger the damage */ int damageToApply; if (self.directHit) { damageToApply = self.explosionMaxDamage + self.directHitBonusDamage; [tank takeDamageAndAdjustHealthBar:damageToApply]; CCLOG(@"Explsoion-> DIRECT HIT with total damage %d", damageToApply); } else { // TODO adjust this... turning out negative for some reason... damageToApply = (1 - (distanceFromExplosionCenter/explosionRadius) * explosionMaxDamage); [tank takeDamageAndAdjustHealthBar:damageToApply]; CCLOG(@"Explosion-> Non direct hit collision with tank"); CCLOG(@"Damage to apply is %d", damageToApply); } // end if } else { CCLOG(@"Explosion-> Explosion distance is larger than explosion radius"); } // end if } // end if Questions: 1) Can this circle to rect collision algorithm be done better? Do I have too many checks? 2) How to calculate the percentage based damage? My current method generates negative numbers occasionally and I don't understand why (Maybe I need more sleep!). But, in my if statement, I ask if distance < explosion radius. When control goes through, distance/radius must be < 1 right? So 1 - that intermediate calculation should not be negative. Appreciate any help/advice!

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